* Rename legacy controller subsystem (LSPController, websocket controller, controller events, and base classes)
into clarified client module for LSP communication
* Structure around LSPManager and LSPManagerClient to handle orchestration and client lifecycle
* Update plugin integration to use LSPManager instead of LSPController
* Simplify architecture by reducing controller indirection
- Remove legacy LSPManager dialog implementation
- Introduce LSPController as the central LSP entry point
- Route UI interactions through lsp_controller.lsp_manager_ui
- Move client lifecycle handling out of ProviderResponseCache
- Simplify completion cache and matcher filtering
- Improve LSP completion item parsing with safer fallbacks
- Modernize typing (Python 3.10 union syntax)
- Remove unused imports and dead code
- Use GLib.idle_add for safe UI scrolling operations
- Minor comment and spelling fixes
- 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
