Add keyboard shortcuts documentation

- Create docs/src/keybinds.md with all keybinds
- Use src/utils/ui/keybinds.ts as source of truth
- Add cross-references in both files to keep them in sync
- Fix intro.md to remove architecture link
- Update SUMMARY.md to include keybinds page

Author: ammario

docs/src/SUMMARY.md

@@ -2,3 +2,4 @@
 
 - [Introduction](./intro.md)
 - [Getting Started](./getting-started.md)
+- [Keyboard Shortcuts](./keybinds.md)

docs/src/intro.md

@@ -12,4 +12,3 @@
 ## Quick Links
 
 - [Getting Started](./getting-started.md)
-- [Architecture Overview](./architecture.md)

docs/src/keybinds.md

@@ -0,0 +1,48 @@
+# Keyboard Shortcuts
+
+cmux is designed to be keyboard-driven for maximum efficiency. All major actions have keyboard shortcuts.
+
+> **Note**: This document should be kept in sync with `src/utils/ui/keybinds.ts`, which is the source of truth for keybind definitions.
+
+## Platform Conventions
+
+- **macOS**: Shortcuts use `⌘` (Command) as the primary modifier
+- **Linux/Windows**: Shortcuts use `Ctrl` as the primary modifier
+
+When documentation shows `Ctrl`, it means:
+- `⌘` (Command) on macOS
+- `Ctrl` on Linux/Windows
+
+## General
+
+| Action | Shortcut |
+|--------|----------|
+| Cancel / Close / Interrupt | `Esc` |
+
+## Chat & Messages
+
+| Action | Shortcut |
+|--------|----------|
+| Send message | `Enter` |
+| New line in message | `Shift+Enter` |
+| Jump to bottom of chat | `Shift+G` |
+
+## Workspaces
+
+| Action | Shortcut |
+|--------|----------|
+| Create new workspace | `Ctrl+N` |
+| Next workspace | `Ctrl+J` |
+| Previous workspace | `Ctrl+K` |
+
+## Modes
+
+| Action | Shortcut |
+|--------|----------|
+| Toggle between Plan and Exec modes | `Ctrl+Shift+M` |
+
+## Tips
+
+- **Vim-inspired navigation**: We use `J`/`K` for next/previous navigation, similar to Vim
+- **Consistent modifiers**: Most workspace/project operations use `Ctrl` as the modifier
+- **Natural expectations**: We try to use shortcuts users would naturally expect (e.g., `Ctrl+N` for new)

src/utils/ui/keybinds.ts

@@ -1,6 +1,9 @@
 /**
  * Centralized keybind utilities for consistent keyboard shortcut handling
  * and OS-aware display across the application.
+ *
+ * NOTE: This file is the source of truth for keybind definitions.
+ * When adding/modifying keybinds, also update docs/src/keybinds.md
  */
 
 /**