feat(kernel): R7b C# walker — csharp module, tree-sitter-c-sharp 0.23.5 pin, csharp default-routed (#1378)

Second R7b port, checklist-first recipe (docs/design/csharp-kernel-port-checklist.md;
parity passed FIRST RUN again). No grammar bump — the #717 vendored wasm verified
table-identical to crate 0.23.5 (ABI 15, STATE_COUNT 8053, node-kind + field tables);
first port with no grammar-prep step. The #237 #if-blanking preParse stays TS-side
via the existing route-point hoist.

Walker preserves bug-for-bug: the single-namespace-node quirks (second namespace
nests under the first, nested namespaces leave no trace, import refs hang off the
namespace node), raw member-access callee texts (this./base./literal receivers,
multi-line fluent chains) with unconditional chain re-encode, deliberate emission
holes (property accessor/expression bodies, ctor initializers, delegates/events/
operators/indexers/local functions, top-level locals), garbage extends refs
((repo) primary-ctor args, BaseDto(Name) record bases, enum : byte), the alias-
import moduleName quirks, nameof-as-call, CSHARP fn-ref spec (+= subscription,
this.X bare-name form, argument layer, initializer lists), C# type-ref engine
(nested-generic returnType failure included), and value-ref shadow pruning.

Gates: sweeps 0-diff serilog 211/216 / Newtonsoft.Json 914/945 / jellyfin
2104/2105 (deferrals match the survey's per-repo predictions — both-arm #if
damage; default --max-deferral 0.1 holds, no c/cpp exemption); full-init dumps
byte-identical ×3 (14.0k/109.1k/210.8k lines); kernel-csharp-parity suite
(torture ×3 + CRLF variants + 8 micro-pins + defer) + csharp grammar-parity row;
full suite 2,608 ×2 under CODEGRAPH_KERNEL_EXPECT=1. DEFAULT_ROUTED += csharp
(11 langs).

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -11,7 +11,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### New Features
 
-- Indexing TypeScript, TSX, JavaScript, JSX, Java, Python, Go, C, C++, and Rust projects is faster: parsing and symbol extraction now run in a native engine when a prebuilt binary is available for your platform (release bundles include one), producing exactly the same graph — verified byte-for-byte against the previous engine on real repositories, from small libraries up to vscode-, dubbo-, django-, git-, protobuf-, tokio-, and rust-analyzer-scale codebases (Lombok-generated members, C function-pointer tables, and Unreal-Engine-style macro-heavy headers included; CUDA and Metal sources ride the C++ path). The speedup is largest on resource-constrained machines like CI runners. No setup needed: platforms without the native binary, and individual files with syntax errors, automatically use the previous engine, and `CODEGRAPH_KERNEL=0` turns the native path off entirely.
+- Indexing TypeScript, TSX, JavaScript, JSX, Java, Python, Go, C, C++, Rust, and C# projects is faster: parsing and symbol extraction now run in a native engine when a prebuilt binary is available for your platform (release bundles include one), producing exactly the same graph — verified byte-for-byte against the previous engine on real repositories, from small libraries up to vscode-, dubbo-, django-, git-, protobuf-, tokio-, rust-analyzer-, and jellyfin-scale codebases (Lombok-generated members, C function-pointer tables, and Unreal-Engine-style macro-heavy headers included; CUDA and Metal sources ride the C++ path). The speedup is largest on resource-constrained machines like CI runners. No setup needed: platforms without the native binary, and individual files with syntax errors, automatically use the previous engine, and `CODEGRAPH_KERNEL=0` turns the native path off entirely.
 - Reference resolution now runs in parallel on large projects. When a project has enough pending references to make it worthwhile (roughly 150k+, typical for big Java/Kotlin/Spring codebases), resolution fans out across worker threads while results are applied in the exact order the single-threaded path would have used — the graph comes out byte-for-byte identical, about twice as fast end-to-end on a 4,000-file Java project in our testing. Small projects keep the single-threaded path automatically (the fan-out costs more than it saves there). Set `CODEGRAPH_NO_PARALLEL_RESOLVE=1` to disable, or `CODEGRAPH_PARALLEL_RESOLVE_MIN=<count>` to tune when it engages.
 - Indexing large projects got another sizeable speedup — about a quarter less wall-clock on the same 4,000-file Java project, with the graph still byte-for-byte identical. Two changes: the database no longer interleaves expensive checkpoint housekeeping into the middle of resolution on a fresh index (it's folded once at the end instead), and while one batch's results are being written out, the worker threads are already resolving the next batch instead of sitting idle.
 - The dynamic-dispatch analysis that runs at the end of indexing (callback, event, and framework wiring) now runs its passes in parallel on large projects, cutting that stage roughly in half there — and a pass that crashes now retries safely instead of failing the whole index, which also makes very large codebases that previously died in this stage more likely to index to completion. Graphs remain byte-for-byte identical.