feat(languages): YAML node-type registry — stepping stone for .scm migration (closes #43)

[Wolfvin]

Closes #43

Ringkasan

Implementasi Approach 2 (YAML node-type registry) dari issue #43 — low-risk stepping stone yang externalise hardcoded tree-sitter node-type lookups ke YAML config. Issue #43 merekomendasikan ini sebagai "DO" action sebelum full .scm migration. Existing parsers tidak berubah — ini purely additive.

Trigger Conditions (all met)

1. P0 bugs [BUG-01] scan: pr.store_scan_result(result) calls non-existent method — SQLite analysis_cache never populated #31, [BUG-02] --deep flag runs HybridEngine twice — LSP findings double-counted #32 — CLOSED ✓
2. Phase 2 [ROADMAP] Phase 2 — Speed (Rust core via PyO3) #22 (Rust core) — CLOSED as 'premature optimization, deferred' ✓ (status clarified)
3. 5+ languages commitment — BOS instructed to proceed ✓
4. Pilot parity — this IS the pilot (Phase A) ✓

Perubahan

New files

File	Purpose
scripts/languages/__init__.py	Package marker, re-exports public API
scripts/languages/node_types.yaml	Config for all 7 tree-sitter languages (python, rust, javascript, typescript, tsx, css, html). Maps semantic categories (function_def, call, import, class_def) to concrete node types.
scripts/languages/loader.py	Cached YAML loader with frozenset caching. get_node_types(lang, cat) → frozenset. NodeTypeError on unknown language/category (fail loud, not silent).
tests/test_node_types.py	32 tests — loader, YAML validity, cache, error handling, BaseParser integration
docs/design/0005-node-type-registry.md	Design doc with trade-offs, Phase B plan

Modified

• scripts/base_parser.py — added find_nodes_by_category(root, language, category) method (additive, backward compatible). Existing find_nodes_by_type / find_nodes_by_types unchanged.

Design

YAML maps semantic categories (stable across languages) to concrete tree-sitter node types (language-specific):

python:
  function_def: [function_definition]
  call: [call]
  import: [import_statement]

rust:
  function_def: [function_item]
  call: [call_expression]
  import: [use_declaration]

Category names (function_def, call, import, class_def) are the same across all languages. This is the design property that the future .scm engine (Phase B) will exploit: a .scm query file for one language maps 1:1 to a category here.

Phase B: .scm Pilot (Next Step, NOT in this PR)

Phase B — Rust .scm pilot — documented in design doc as the next step. Not implemented in this PR karena tree-sitter Query API tidak available di semua environments. YAML registry (Phase A) works without tree-sitter at runtime — it's pure config.

Verifikasi

• tests/test_node_types.py: 28 passed, 4 skipped (BaseParser tests need tree-sitter, which is optional in minimal environments per CONTEXT.md)
• sync_command_count.py --check: clean (78 commands, no new command added)
• check_design_doc.py: PASS
• All 7 tree-sitter languages covered in YAML config

Trade-offs (from design doc)

• Alternative A (full .scm migration): 2-3 week effort, only replaces Layer 1. Issue [PROPOSAL] Adopt tree-sitter query files (.scm) for node discovery — phased rollout, defer full migration until triggers met #43 says 'Do not migrate existing parsers now' — this PR respects that.
• Alternative B (status quo): Zero new files but doesn't prepare ground for .scm migration.
• Chosen (YAML registry): Lowest risk, purely additive, creates category abstraction that .scm will reuse. Adding a language = adding YAML lines, not Python.

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[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud