feat(kernel): R1 scaffold — napi-rs extraction kernel, buffer contract, routing + fallback, grammar-parity CI

Phase 0 of the Rust extraction-kernel migration (docs/design/
rust-kernel-migration-plan.md, now checked in with §3a recording the
shipped state):

- codegraph-kernel/ napi-rs crate: extractFile(path, content, language)
  → five flat buffers (meta/nodes/edges/refs/arena), one JS boundary
  crossing per file. Node ids computed Rust-side, byte-identical to
  generateNodeId (pinned by test vector). Reserved per-node metrics slot
  for the Arc 3.2 code-metrics work.
- Generic .scm-driven emitter (@def.<kind>/@name/@ref.<kind> captures,
  byte-range scope stack → ::-joined qualified names, contains edges,
  refs attributed to the innermost enclosing symbol). Seed TS/JS queries
  are smoke-level; R2 replaces them with the full port.
- Routing seam in extractFromSource with per-file wasm fallback.
  DEFAULT_ROUTED is empty — no behavior change until a language passes
  its equivalence gate (R3). Dev opt-in: CODEGRAPH_KERNEL_LANGS. Kill
  switch: CODEGRAPH_KERNEL=0. Loader verifies ABI + kind tables before
  routing; EDGE_KINDS became a runtime array because kind order is now
  wire contract.
- Grammar-source parity: vendored TS/TSX/JS wasm grammars built from the
  exact crate revisions (tree-sitter-typescript v0.23.2,
  tree-sitter-javascript v0.25.0, checked-in parser.c, ts-cli 0.25.10) —
  the tree-sitter-wasms builds were 2023-era, which the new
  kernel-grammar-parity test caught on day one. Production TS/JS parsing
  gets 2.5 years of grammar fixes; full suite green (2456 tests).
- Build/release wiring: scripts/build-kernel.sh + npm run build:kernel;
  release.yml kernel prebuild matrix (continue-on-error — the kernel is
  optional everywhere, bundles fall back to the wasm path); bundles stage
  lib/kernel/codegraph-kernel.node; release job runs the kernel suites
  with CODEGRAPH_KERNEL_EXPECT=1.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/extraction/grammars.ts

@@ -271,10 +271,23 @@ export async function initGrammars(): Promise<void> {
  * nix-community/tree-sitter-nix @ 3d0173d (MIT) with tree-sitter-cli 0.25.10
  * (`generate` + `build --wasm`, ABI 15 — upstream's checked-in parser.c is
  * still ABI 13; all 54 upstream corpus tests pass on the regenerated parser).
+ *
+ * TypeScript/TSX/JavaScript (+jsx, which shares the javascript grammar): the
+ * tree-sitter-wasms builds are 2023-era (^0.20.x); we vendor wasm built from
+ * the SAME grammar revisions the native extraction kernel compiles
+ * (codegraph-kernel/Cargo.toml), so the kernel path and the wasm fallback
+ * parse identically and per-language routing stays graph-neutral:
+ *   - tree-sitter/tree-sitter-typescript v0.23.2 (f975a62) → typescript + tsx
+ *   - tree-sitter/tree-sitter-javascript v0.25.0 (44c892e) → javascript + jsx
+ * Built from each repo's CHECKED-IN parser.c (no `generate`) with
+ * tree-sitter-cli 0.25.10 `build --wasm` — the same tables crates.io compiles.
+ * The kernel-grammar-parity test asserts this alignment; bump the crate and
+ * the vendored wasm together.
  */
 const VENDORED_WASM_LANGS: ReadonlySet<GrammarLanguage> = new Set([
   'pascal', 'scala', 'lua', 'luau', 'csharp', 'r', 'cfml', 'cfscript', 'cfquery',
   'cobol', 'vbnet', 'erlang', 'terraform', 'arkts', 'nix',
+  'typescript', 'tsx', 'javascript', 'jsx',
 ]);
 
 /** Absolute path of a language's grammar WASM (vendored or tree-sitter-wasms). */