feat(tree-sitter, views): initialize AST on focus and emit source view creation event

- Add set_ast helper to centralize Tree-sitter parsing logic
- Parse and attach AST on FocusedViewEvent and TextChangedEvent
- Request file from buffer on view focus before parsing
- Fix parser guard condition in get_parser (handle missing language properly)

- Emit CreatedSourceViewEvent when a new source view is added
- Register CreatedSourceViewEvent in DTO exports

- Update TODO:
  - Remove completed collapsible code blocks task
  - Add fix note for code block icon desync issue

chore:
- Add scaffolding for code_fold UI plugin
- Add created_source_view_event DTO

TODO.md

@@ -1,6 +1,5 @@
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 ### Add
-1. Add Collapsable code blocks
 1. Add Godot LSP Client
 1. Add Terminal plugin
 1. Add Plugin to <Shift\><Ctrl\>| and <Ctrl\>| to split views up, down, left, right
@@ -14,5 +13,6 @@ ___
 ___
 ### Fix
 - Fix on lsp client unload to close files lsp side and unload server endpoint
+- Fix Collapsable code blocks icon desync on new/old lines or text cut/pasted
 
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