Add `meta.*` category scopes (`comment`, `cosmetic`, `network`) and exception flag to Adblock TextMate grammar

Introduce three category wrapper scopes and one orthogonal exception flag into `adblock.yaml-tmlanguage` using `begin`/`end` blocks around existing patterns (preserving all leaf scopes), then update and extend the grammar test suite with category-aware assertions across all rule families.

**Key changes**:
- Replace top-level `patterns` with `commentRules`, `cosmeticRules`, `networkRules` wrappers carrying `meta..adblock`
- Add `meta.exception.adblock` for allowlist rules (`@@` network, `#@#`/`$@$` cosmetic variants)
- Add scope constants (`META_COMMENT_SCOPE`, `META_COSMETIC_SCOPE`, `META_NETWORK_SCOPE`, `META_EXCEPTION_SCOPE`)
- Update all existing test scope arrays with category scopes
- Add new `category-scopes.test.ts` cross-cutting suite covering every rule family + exception flag