fix(code-index): prevent indexing memory leaks

[hannesrudolph]

Related to Roo-Code PR #7666 (terminal output memory retention), this audits the codebase indexing feature for similar long-lived retention and fixes two leak patterns:

1. .rooignore watcher lifecycle

• Avoid creating file watchers during one-shot directory scans.
• Ensure ignore controller watchers are disposed when recreating/disposing the code index services.

2. web-tree-sitter parse tree disposal

• Ensure parse trees are deleted after use to prevent WASM heap growth.

Key changes:

• src/core/ignore/RooIgnoreController.ts: add watch option to skip watcher creation.
• src/services/code-index/processors/scanner.ts: use watch:false and dispose in finally.
• src/services/code-index/processors/file-watcher.ts + src/services/code-index/manager.ts: explicit ownership + disposal of shared RooIgnoreController.
• src/services/code-index/processors/parser.ts + src/services/tree-sitter/index.ts: delete parse trees.

Tests:

• Updated scanner/file-watcher/parser tests and added tree-sitter tree-disposal test.

---

Important

Fix memory leaks in code indexing by controlling file watcher creation and ensuring parse tree disposal.

• Behavior:
  • Avoid creating file watchers during one-shot directory scans in RooIgnoreController.
  • Ensure RooIgnoreController watchers are disposed in manager.ts and file-watcher.ts.
  • Ensure parse trees are deleted after use in parser.ts and index.ts.
• Options:
  • Add watch option to RooIgnoreController to control watcher creation.
• Tests:
  • Update tests in file-watcher.spec.ts, parser.spec.ts, and scanner.spec.ts.
  • Add tree-disposal.spec.ts to test parse tree disposal.

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Re-review complete (90f010f). No issues flagged in the latest changes.

• No issues to resolve

Previous reviews

• 2eec910: Review #1

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