feat(kernel): R4 — Java port with Lombok synthesis, gate passed, default-on

Java joins the native kernel (codegraph-kernel/src/java.rs), mirroring
the wasm extractor's Java paths bug-for-bug: package namespaces,
imports, javadoc, annotations→decorates, type_list inheritance,
static-final constants, enum constants, anonymous classes (including
the TS side's 0-based-line quirk on the extends ref), method_invocation
calls with the this.field unwrap and the Foo.getInstance().bar() chain
encoding (#645/#608), static-member value reads, method-reference
fn-refs (#756), value-reference edges, and the full Lombok member
synthesizer (#912: Getter/Setter/Data/Value/Builder/ToString/
EqualsAndHashCode/Slf4j-family with taken-member dedup). The shared
docstring/textutil modules moved to crate level. Grammar:
tree-sitter-java 0.23.5, with the wasm grammar vendored from the same
tag (parser.c sha-matched) replacing tree-sitter-wasms' 2023-era build.

Gate (plan §4c): extraction sweeps 100% — gson 262/262, retrofit
341/341, dubbo 4,048/4,048 — plus a Java torture fixture in npm test;
full-init dump-diffs byte-identical on gson (49,766 rows), retrofit
(62,735), and dubbo (441,266 rows); all R2/R3 repos re-verified; Linux
container runs all 23 kernel tests green under CODEGRAPH_KERNEL_EXPECT=1.

The gate caught a real cross-language bug: fn-ref dedupe and value-ref
self-target checks must compare node ID STRINGS, not node-table rows —
ids collide for same-(kind, name, line) nodes, which minified one-line
bundles hit routinely (retrofit's website JS exposed it; latent in the
TS/JS walker since R2, never released). Fixed in both walkers.

Benchmark honesty: dubbo fresh-init on an 11-core Mac is ~flat
(parse-loop wall 5,020→4,394ms; total ~11.3s both arms) because that
wall is main-thread-bound (reads + store), not worker-CPU-bound — the
§6 expectation assumed otherwise. Where worker CPU binds the kernel
delivers: dubbo on a 2-CPU/6GB container drops 27.8-28.6s → 22.3-22.8s
(~1.25×). The identified lever for the many-core headline is decoding
kernel buffers directly into store rows (skipping per-node JS object
materialization); the buffer contract already carries everything.

DEFAULT_ROUTED now includes java. Full suite: 2,467 tests pass.

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

scripts/kernel-parity.mjs

@@ -39,11 +39,11 @@ if (paths.length === 0) {
   process.exit(2);
 }
 
-const KERNEL_LANGS = new Set(['typescript', 'tsx', 'javascript', 'jsx']);
+const KERNEL_LANGS = new Set(['typescript', 'tsx', 'javascript', 'jsx', 'java']);
 const EXTS = new Map([
   ['.ts', 'typescript'], ['.mts', 'typescript'], ['.cts', 'typescript'],
   ['.tsx', 'tsx'], ['.js', 'javascript'], ['.mjs', 'javascript'],
-  ['.cjs', 'javascript'], ['.jsx', 'jsx'],
+  ['.cjs', 'javascript'], ['.jsx', 'jsx'], ['.java', 'java'],
 ]);
 
 /** Collect candidate files. */