* address TODO item for split_pane_manager plugin and bound keys
* add split_pane_manager plugin with create/close split view commands
* move sibling focus/move commands from core into plugin system
* remove legacy toggle_source_view plugin
* redesign EditorsContainer to use simpler Box-based layout
* refactor source view API to return (scrolled_window, source_view)
* add source view lifecycle events (create/remove/removed)
* rename GetNewCommandSystemEvent → CreateCommandSystemEvent
* update CommandsController to support command system creation and cleanup
* ensure command systems are removed with their source views
* improve focus border handling across sibling chains
* update telescope integration for new source view structure
* clean up container imports and initialization logic
* remove old keybindings and align with new split pane workflow
- Rename GodotHandler to GDScriptHandler in LSP client
- Fix unload() method naming in nanoesq_temp_buffer plugin
- Return manifest_meta in manifest_manager for manual launch plugins
- Properly destroy tabs_widget, viewport, and scrolled_win on unload
- Refactor plugin removal to search all manifest lists and fix cleanup order
- Fix widget reference in plugins_ui (use child instead of box)
- Moved plugins to proper sub groups (autopairs, code_minimap, colorize, commentzar, info_bar, markdown_preview, prettify_json, search_replace, tabs_bar, telescope, toggle_source_view, lsp_client)
- Add filter_out_loaded_files to prevent opening already-loaded files
- Add INDEPENDENT source view state
- Fix cursor scroll position on buffer switch
- Fix signal blocking during file load
- Fix word boundary in completion provider
- Refactor code events into single events module
