refactor(code): move temp cut buffer feature and clean up related code

- Moved cut_to_temp_buffer and paste_temp_buffer commands to plugin
- Remove temporary cut buffer logic from SourceView
- Remove related keybindings (Ctrl+K / Ctrl+U)
- Fix word-end detection in ProviderResponseCacheBase to avoid extending past line end
- Improve completion controller to support RequestCompletionEvent with optional provider filtering
- Add GetActiveViewEvent handling in SourceViewsController
- Ensure view scrolls to cursor after buffer switch via GLib.idle_add
- Emit focus-in-event after DnD file load to restore focus behavior
- Prevent "buffer" pseudo-path from interfering with loaded file filtering
- Remove obsolete AGENTS.md from LSP manager plugin

plugins/code/commands/nanoesq_temp_buffer/manifest.json

@@ -0,0 +1,7 @@
+{
+    "name": "Nanoesq Temp Buffer",
+    "author": "ITDominator",
+    "version": "0.0.1",
+    "support": "",
+    "requests": {}
+}