feat(code): improve comment toggling, terminal navigation, and editor event wiring

- Refactor Commenter toggle logic for line and multi-line comments
  - Preserve indentation and cursor position
  - Improve handling of existing comment detection and removal
  - Simplify bounds vs line comment dispatch

- Enhance terminal project navigation
  - Add project marker detection via Gio file traversal
  - Implement go-to-project-or-home behavior (Home key shortcut)
  - Automatically `cd` into detected project root or home directory
  - Wire terminal widget navigation through VteWidget

- Improve terminal integration
  - Pass emit_to into terminals view for event dispatching
  - Add ability for VteWidget to trigger project navigation

- Update split pane shortcut
  - Change close split view binding to Alt+\

- Add editor event support
  - Emit `text_insert` event from SourceFile on insert
  - Add new TextInsertEvent DTO and register in event system

- Misc cleanup
  - Improve imports and structure in terminals module
  - Add project marker list and filesystem traversal helpers

plugins/code/commands/split_pane/plugin.py

@@ -55,7 +55,7 @@ class Plugin(PluginCode):
             command_name = "close_split_view",
             command      = _close_split_view,
             binding_mode = "released",
-            binding      = "<Shift><Control>w"
+            binding      = "<Alt>\\"
         )
 
         self.emit_to("source_views", event)