Release v1.23.0 (#31)

* Rename cmuxterm to cmux across entire codebase

- Rename GitHub repos: manaflow-ai/cmuxterm -> manaflow-ai/cmux,
  manaflow-ai/homebrew-cmuxterm -> manaflow-ai/homebrew-cmux
- Rename bundle IDs: com.cmuxterm.app -> com.cmux.app
- Rename CLI: CLI/cmuxterm.swift -> CLI/cmux.swift
- Rename homebrew submodule: homebrew-cmuxterm -> homebrew-cmux
- Update all socket paths: /tmp/cmuxterm*.sock -> /tmp/cmux*.sock
- Update all GitHub URLs, DMG names, Sparkle URLs
- Update all source files, scripts, tests, docs, CI workflows

* Bump version to 1.23.0

Sources/Update/UpdatePopoverView.swift

@@ -52,7 +52,7 @@ fileprivate struct PermissionRequestView: View {
                 Text("Enable automatic updates?")
                     .font(.system(size: 13, weight: .semibold))
 
-                Text("cmuxterm can automatically check for updates in the background.")
+                Text("cmux can automatically check for updates in the background.")
                     .font(.system(size: 11))
                     .foregroundColor(.secondary)
                     .fixedSize(horizontal: false, vertical: true)