feat(kernel): R2 — full TypeScript/JavaScript extraction port, byte-parity with the wasm path

Replaces the R1 seed .scm emitter with a bespoke Rust walker
(codegraph-kernel/src/tsjs/) that mirrors TreeSitterExtractor's TS/JS
paths function-for-function: declarations (incl. #808 field/property
classification), qualified names, docstrings (#780 wrapper climbs),
signatures, imports/re-exports + per-binding refs, calls with
receiver-qualified callees (#1230 literal-receiver skip), instantiations,
decorators, inheritance, type annotations (#381), type-alias members +
tuple contracts (#359/#634), React component recognition (#841
forwardRef/memo/styled), object-of-functions / zustand-through-middleware
/ RTK Query endpoints + generated hooks / vuex + pinia store shapes,
function-as-value capture with the flush gate (#756), and value-reference
edges with the shadow prune (#895/#897). The generic query emitter is
deleted — extraction parity needs logic .scm can't express; future
languages get walkers too (migration plan §4a).

Positions and JS string-slice semantics are emitted in UTF-16 code units
natively, so kernel output is byte-identical to web-tree-sitter's — no
column diff class exists.

Parity evidence (macOS): scripts/kernel-parity.mjs (full-object multiset
diff per file) — this repo 353/353 files, excalidraw 643/643 (10,650
nodes / 10,726 edges / 68,307 refs), plus torture fixtures checked into
__tests__/fixtures/kernel-parity/ and enforced in npm test by
kernel-tsjs-parity.test.ts. The strict compare caught one real decoder
bug the loose harness missed: refs must NOT carry denormalized
filePath/language at the extractFromSource seam (the store fills them).

Perf: extraction 2.6× single-thread on excalidraw (487ms vs 1,255ms,
identical outputs). Routing stays opt-in (CODEGRAPH_KERNEL_LANGS) until
the R3 equivalence gate (large repo, DB dump-diff, retrieval invariants,
agent A/B, Linux/Windows) passes.

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

codegraph-kernel/src/buffers.rs

@@ -316,6 +316,15 @@ impl Tables {
     }
 }
 
+/// One file's encoded tables, ready to hand across the JS boundary.
+pub struct EmitOut {
+    pub meta: Vec<u8>,
+    pub nodes: Vec<u8>,
+    pub edges: Vec<u8>,
+    pub refs: Vec<u8>,
+    pub arena: Vec<u8>,
+}
+
 pub fn build_meta(t: &Tables, arena_len: u32, errors_json: StrRef, duration_ms: f64) -> Vec<u8> {
     let mut m = Vec::with_capacity(META_SIZE);
     m.push(KERNEL_ABI_VERSION);