fix(index): yield during resolution so the liveness watchdog can't kill a valid large index (#1091) (#1105)

The #850 liveness watchdog SIGKILLs a process whose main-thread event loop
stalls past its window (60s default). It was extended to `index`/`init` in
#999, but reference resolution and callback-edge synthesis run synchronously
on that same thread — so on a large repo a legitimate, in-progress index gets
killed, and users had to disable the watchdog entirely (CODEGRAPH_NO_WATCHDOG=1).

Make the long synchronous spans yield cooperatively so the heartbeat keeps
firing during real work, while a genuinely wedged span (which never reaches a
yield) still trips the watchdog:

- synthesizeCallbackEdges yields between its whole-graph passes, and the heavy
  scanners (closure-collection, event-emitter, JSX-child, object-registry,
  field-channel) yield within their loops;
- batched resolution sub-chunks each batch with yields;
- the deferred chained-call and this-member post-passes yield per ref.

Behaviour-preserving — only timing changes; node/edge counts are identical.

Validated end-to-end with the real watchdog armed at the default 60s: the
released build is SIGKILLed partway through indexing the Swift compiler (27k
files, ~1.1M edges) and the TypeScript compiler, while the fixed build indexes
both to completion.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -11,6 +11,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixes
 
+- Indexing a large project no longer gets killed partway through with a "Main thread unresponsive — killing the wedged process" message. The safety watchdog that stops a genuinely stuck index was mistaking slow-but-normal work for a hang: on a big repo, linking up references and cross-file relationships can legitimately run for a while, and that work now regularly yields so the watchdog can tell real progress from a true stall. Projects that previously failed to finish `codegraph init` / `codegraph index` (and had to fall back to `CODEGRAPH_NO_WATCHDOG=1`) now complete normally, while a genuinely hung process is still caught. Thanks @zmcrazy, @YoungLiao, and @GeeLab-Mob for the reports. (#1091)
 - On Windows, a console window no longer briefly flashes when CodeGraph runs as a background MCP server. When the npm launcher started the bundled runtime — which happens every time an editor starts the server or reconnects after the daemon idles out — and during its self-heal step that extracts a missing platform bundle, Windows would pop up a black console (conhost) window for a moment. Both now launch hidden, matching how the daemon already behaved; the browser-open step of `codegraph login` was hardened the same way. Thanks @luoyerr for the report and root-cause analysis. (#1092)
 - C++ forward declarations no longer crowd out the real class definition. A `class Foo;` forward declaration — common in large C++ and Unreal Engine codebases, where a heavily used class is forward-declared across dozens of headers — was indexed as its own class node every time it appeared. So exploring that class returned mostly forward-declaration sites, and could even pick one of them as the representative for blast-radius, burying the actual definition and its members and callers. Bodiless forward declarations are now skipped for C and C++, exactly as forward-declared structs and enums already were, so only the real definition is indexed. Languages where a class with no body is a complete definition — such as Kotlin's `class Empty` and Scala — are unaffected. Thanks @luoyxy for the report and root-cause analysis. (#1093)
 - C++ methods that return a reference, and user-defined conversion operators, are now indexed under their correct names. An inline getter like `const FGameplayTagContainer& GetActiveTags() const` — everywhere in Unreal Engine headers — was indexed as `& GetActiveTags() const` instead of `GetActiveTags`, and a conversion operator like `operator EALSMovementState() const` kept its trailing `() const` instead of reading `operator EALSMovementState`. In both cases the garbled name meant you couldn't find the symbol by name and its callers weren't linked. Both now read cleanly, matching how pointer-returning and value-returning methods already worked. (#1096)