docs(coding-agent): document missing hotkeys in README and /hotkeys

- Add Ctrl+L (Open model selector) to /hotkeys command
- Add Alt+Enter (Queue follow-up message) to keyboard shortcuts table
- Add PageUp/PageDown (Scroll by page) to all documentation sections

packages/coding-agent/README.md

@@ -343,6 +343,7 @@ Both modes are configurable via `/settings`: "one-at-a-time" delivers messages o
 | Option+Left/Right | Move by word |
 | Ctrl+A / Home / Cmd+Left | Start of line |
 | Ctrl+E / End / Cmd+Right | End of line |
+| PageUp / PageDown | Scroll by page |
 
 **Editing:**
 
@@ -374,6 +375,7 @@ Both modes are configurable via `/settings`: "one-at-a-time" delivers messages o
 | Ctrl+T | Toggle thinking block visibility |
 | Ctrl+G | Edit message in external editor (`$VISUAL` or `$EDITOR`) |
 | Ctrl+V | Paste image from clipboard |
+| Alt+Enter | Queue follow-up message |
 | Alt+Up | Restore queued messages to editor |
 
 ### Custom Keybindings
@@ -399,6 +401,8 @@ All keyboard shortcuts can be customized via `~/.pi/agent/keybindings.json`. Eac
 | `cursorWordRight` | `alt+right`, `ctrl+right` | Move cursor word right |
 | `cursorLineStart` | `home`, `ctrl+a` | Move to line start |
 | `cursorLineEnd` | `end`, `ctrl+e` | Move to line end |
+| `pageUp` | `pageUp` | Scroll up by page |
+| `pageDown` | `pageDown` | Scroll down by page |
 | `deleteCharBackward` | `backspace` | Delete char backward |
 | `deleteCharForward` | `delete` | Delete char forward |
 | `deleteWordBackward` | `ctrl+w`, `alt+backspace` | Delete word backward |