Improve docs page meta descriptions for SEO

Add keyword-rich descriptions mentioning Ghostty, macOS, AI agents,
and specific features to each docs page for better search ranking.

web/app/docs/api/page.tsx

@@ -4,7 +4,8 @@ import { Callout } from "../../components/callout";
 
 export const metadata: Metadata = {
   title: "API Reference",
-  description: "CLI and socket API reference for cmux",
+  description:
+    "cmux CLI and Unix socket API reference. Workspace management, split panes, input control, notifications, environment variables, and detection methods.",
 };
 
 function Cmd({

web/app/docs/changelog/page.tsx

@@ -4,7 +4,8 @@ import path from "path";
 
 export const metadata: Metadata = {
   title: "Changelog",
-  description: "Release notes and version history for cmux",
+  description:
+    "cmux release notes and version history. New features, bug fixes, and changes for the native macOS terminal.",
 };
 
 interface ChangelogSection {

web/app/docs/concepts/page.tsx

@@ -4,7 +4,7 @@ import { CodeBlock } from "../../components/code-block";
 export const metadata: Metadata = {
   title: "Concepts",
   description:
-    "Understanding cmux's window, workspace, pane, and surface hierarchy",
+    "How cmux organizes terminals: windows, workspaces, panes, and surfaces. The hierarchy behind the sidebar, splits, and socket API.",
 };
 
 export default function ConceptsPage() {

web/app/docs/configuration/page.tsx

@@ -4,7 +4,8 @@ import { Callout } from "../../components/callout";
 
 export const metadata: Metadata = {
   title: "Configuration",
-  description: "Configure cmux appearance and behavior",
+  description:
+    "Configure cmux via Ghostty config files. Font, theme, colors, split pane styling, scrollback, and app settings for automation mode.",
 };
 
 export default function ConfigurationPage() {

web/app/docs/getting-started/page.tsx

@@ -5,7 +5,8 @@ import { DownloadButton } from "../../components/download-button";
 
 export const metadata: Metadata = {
   title: "Getting Started",
-  description: "Install and set up cmux on macOS",
+  description:
+    "Install cmux, the native macOS terminal for AI coding agents. Homebrew, DMG download, CLI setup, and auto-updates via Sparkle.",
 };
 
 export default function GettingStartedPage() {

web/app/docs/keyboard-shortcuts/page.tsx

@@ -3,7 +3,8 @@ import { KeyboardShortcuts } from "../../keyboard-shortcuts";
 
 export const metadata: Metadata = {
   title: "Keyboard Shortcuts",
-  description: "Complete list of cmux keyboard shortcuts",
+  description:
+    "All cmux keyboard shortcuts for workspaces, surfaces, split panes, browser, notifications, find, and window management on macOS.",
 };
 
 export default function KeyboardShortcutsPage() {

web/app/docs/notifications/page.tsx

@@ -4,7 +4,8 @@ import { Callout } from "../../components/callout";
 
 export const metadata: Metadata = {
   title: "Notifications",
-  description: "Desktop notifications in cmux for AI agents and scripts",
+  description:
+    "Send desktop notifications from AI agents and scripts in cmux. CLI, OSC 99/777 escape sequences, and Claude Code hooks integration.",
 };
 
 export default function NotificationsPage() {