Add cmux omo command for oh-my-openagent integration (#2087)

* Add `cmux omo` command for OpenCode + oh-my-openagent integration

Same pattern as `cmux claude-teams`: creates a tmux shim so
oh-my-openagent's TmuxSessionManager spawns agents as native cmux
splits instead of tmux panes. Sets TMUX/TMUX_PANE env vars, prepends
shim to PATH, and execs into opencode.

Closes https://github.com/manaflow-ai/cmux/issues/2085

* Auto-install oh-my-opencode plugin when running cmux omo

Before launching opencode, cmux omo now:
- Checks if oh-my-opencode is registered in ~/.config/opencode/opencode.json
- If not, creates/updates the config with the plugin entry
- Checks if the npm package is installed in node_modules
- If not, runs bun add (or npm install) to install it
- Then proceeds with tmux shim setup and exec

* Use shadow config dir to avoid modifying user's opencode setup

Instead of writing directly to ~/.config/opencode/opencode.json,
cmux omo now creates a shadow config at ~/.cmuxterm/omo-config/ that
layers oh-my-opencode on top of the user's existing config. Symlinks
node_modules, package.json, bun.lock, and plugin config from the
original dir. Sets OPENCODE_CONFIG_DIR to the shadow directory.

Running plain `opencode` remains unaffected.

* Add Agent Integrations docs section with Claude Code Teams and oh-my-opencode pages

Adds sectioned sidebar navigation to the docs site. The new Agent
Integrations section contains separate pages for cmux claude-teams and
cmux omo, documenting usage, tmux shim mechanics, directory layout,
environment variables, and the shadow config approach. Both pages
include a nightly-only warning. Full English and Japanese translations,
nav item keys added to all 19 locales.

* Remove uppercase from sidebar section headers

* Add more spacing above and below sidebar section headers

* Enable tmux mode in oh-my-opencode config, improve docs

- cmux omo now writes tmux.enabled=true to the shadow oh-my-opencode.json
  config. Without this, oh-my-openagent's TmuxSessionManager won't spawn
  visual panes even though $TMUX is set (the config defaults to false).
- Nightly warnings now link to /nightly instead of generic text.
- Added "What you get" section to oh-my-opencode docs explaining the
  visual pane behavior (auto-layout, idle cleanup, queueing).
- Added tmux.enabled step to first-run and how-it-works sections.

* Add terminal-notifier shim to route oh-my-openagent notifications to cmux

oh-my-openagent sends macOS notifications via terminal-notifier
(args: -title <t> -message <m> [-activate <id>]). The shim in
~/.cmuxterm/omo-bin/terminal-notifier intercepts these calls and
routes them through cmux notify, so notifications appear in cmux's
sidebar panel instead of as raw macOS notifications.

* Add pane geometry to tmux-compat for oh-my-openagent grid planning

oh-my-openagent's TmuxSessionManager needs pane geometry (columns,
rows, position, window dimensions) to decide where to spawn agent
panes. Without this data, agents run headlessly.

Server side:
- pane.list v2 response now includes pixel_frame, cell_size, columns,
  rows per pane, plus container_frame at the top level
- Uses BonsplitController.layoutSnapshot() for pixel geometry and
  ghostty_surface_size() for terminal grid dimensions

CLI side:
- tmuxEnrichContextWithGeometry() computes character-cell positions
  from pixel frames and cell dimensions for tmux format variables
  (pane_width, pane_height, pane_left, pane_top, pane_active,
  window_width, window_height)
- list-panes now resolves pane targets (%uuid) via tmuxResolvePaneTarget
  instead of failing with "Workspace not found"
- display-message enriched with geometry for format strings like
  #{pane_width},#{window_width}
- tmux -V now returns "tmux 3.4" (needed by oh-my-openagent's
  tmux-path-resolver verification)

* Add socket tests for tmux-compat pane geometry

6 tests verifying the geometry enrichment works end-to-end:
- pane.list returns pixel_frame, columns, rows, cell_size, container_frame
- tmux -V returns version string
- list-panes -F renders geometry format variables as integers
- list-panes -t %<uuid> resolves pane targets
- display -p renders pane_width and window_width
- After split, two panes have different positions and halved widths

All 6 pass on macmini (cmux-macmini).

* Handle tmux -V in shim script directly (no socket needed)

oh-my-openagent's tmux-path-resolver runs tmux -V to verify the binary
works. The __tmux-compat handler requires a socket connection, which
may not be established at verification time. Handle -V in the bash
shim directly to avoid the socket dependency.

* Lower default tmux pane min widths for cmux omo

oh-my-openagent defaults: main_pane_min_width=120, agent_pane_min_width=40,
requiring 161+ columns. Most terminal windows are narrower, causing
decideSpawnActions to return canSpawn=false and defer agents forever.

cmux omo now sets: main_pane_min_width=60, agent_pane_min_width=30,
main_pane_size=50, requiring only 91 columns. Also moved tmux -V
handling into the bash shim to avoid needing a socket connection for
the version check.

* Resolve merge conflicts with main (main-vertical layout, focus param)

- Keep upstream main-vertical layout anchoring from #2119
- Keep upstream focus param (v2Bool) instead of no_focus
- Combine with our -d flag handling: -d sets focus=false
- Include customCommands nav item from main

* Implement select-layout equalize and resize-pane absolute width

When oh-my-openagent spawns agent panes, it calls select-layout
main-vertical after each split to redistribute panes evenly, then
resize-pane -x <columns> to set the main pane width. Both were
previously no-ops, causing cascading uneven splits.

Server side:
- Add workspace.equalize_splits v2 API that calls the existing
  TabManager.equalizeSplits (sets all dividers to 0.5)

CLI side:
- select-layout now calls workspace.equalize_splits before tracking
  main-vertical state
- resize-pane -x <columns> without directional flags now computes
  the pixel delta from current to desired width and resizes accordingly

* Fix equalize to use proportional divider positions

The previous equalize set all dividers to 0.5, which in a right-
recursive binary tree (from successive splits) gives 50/25/12.5/6.25%
instead of equal sizes.

New algorithm counts leaf panes on each side of each split and sets
the divider to N_left / (N_left + N_right). For 5 panes in a chain:
1/5, 1/4, 1/3, 1/2, giving each pane exactly 20%.

* Fix select-layout main-vertical to only equalize vertical splits

The proportional equalize was treating the top-level horizontal split
(main vs agent column) the same as vertical splits, setting the main
pane to 1/6 of the window with 5 agents.

For main-vertical layout, only equalize vertical splits (the agent
column), leaving the horizontal main/agent divider untouched. The
subsequent resize-pane -x handles the main pane width.

workspace.equalize_splits now accepts an optional orientation filter
("vertical" or "horizontal") to scope which splits get equalized.

* Re-equalize agent column after kill-pane

* Address PR review comments

- Fix cmux omo --help: remove omo from the help-bypass guard so
  --help shows usage text instead of trying to launch opencode
- Don't overwrite unreadable opencode.json: fail with an error
  instead of silently resetting to empty config
- Drain installer pipes concurrently before waitUntilExit to
  prevent deadlock from full pipe buffers during bun/npm install

---------

Co-authored-by: Lawrence Chen <lawrencecchen@users.noreply.github.com>

Resources/Localizable.xcstrings

@@ -132,6 +132,23 @@
         }
       }
     },
+    "cli.omo.usage": {
+      "extractionState": "manual",
+      "localizations": {
+        "en": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Usage: cmux omo [opencode-args...]\n\nLaunch OpenCode with oh-my-openagent in a cmux-aware environment.\n\noh-my-openagent orchestrates multiple AI models as specialized agents in\nparallel. This command sets up a tmux shim so agent panes become native\ncmux splits with sidebar metadata and notifications.\n\nThis command:\n  - sets a tmux-like environment so oh-my-openagent uses cmux splits\n  - prepends a private tmux shim to PATH\n  - forwards all remaining arguments to opencode\n\nThe tmux shim translates tmux window/pane commands into cmux workspace\nand split operations in the current cmux session.\n\nExamples:\n  cmux omo\n  cmux omo --continue\n  cmux omo --model claude-sonnet-4-6"
+          }
+        },
+        "ja": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "使い方: cmux omo [opencode-args...]\n\ncmux 対応の環境で OpenCode と oh-my-openagent を起動します。\n\noh-my-openagent は複数の AI モデルを専門エージェントとして並列に\nオーケストレーションします。このコマンドは tmux shim を設定し、\nエージェントのペインをネイティブの cmux split に変換します。\n\nこのコマンドは次を行います:\n  - oh-my-openagent が cmux の split を使うよう tmux 風の環境を設定\n  - 専用の tmux shim を PATH の先頭に追加\n  - 残りの引数をそのまま opencode に渡す\n\ntmux shim は、tmux の window/pane コマンドを、現在の cmux セッション内の\nworkspace と split 操作に変換します。\n\n例:\n  cmux omo\n  cmux omo --continue\n  cmux omo --model claude-sonnet-4-6"
+          }
+        }
+      }
+    },
     "applescript.error.disabled": {
       "extractionState": "manual",
       "localizations": {