feat(resolution): infer local-variable receiver types across languages (#1108) (#1109)

Instance calls through a local variable — `const lg = new Logger();
lg.log();` — only resolved to the method in C++. Every other language
produced no `calls` edge, because the resolver had no way to learn the
receiver variable's type, so such calls were missing from callers,
impact/blast-radius, and explore flow traces.

Local variables aren't indexed as nodes (node-explosion), so — like the
existing C++ inferrer — this reads the enclosing function's source and
matches the receiver's declaration/initializer to recover its type, then
hands it to resolveMethodOnType. That validates the method actually
exists on the inferred type, so a mis-inference yields no edge, which is
what lets the per-language patterns stay simple. The scan is bounded to
the enclosing scope so a same-named variable in another function can't
leak in.

Generalizes the C++-only path in matchMethodCall into a language dispatch:
C++ keeps its dedicated header-aware inferrer; a new shared
inferLocalReceiverType covers TypeScript, JavaScript, Python, Java, C#,
Kotlin, Swift, Go, Rust, Dart, Scala, and PHP, matching each language's
declaration shapes (`= new T`, `= T(...)`, `= T.new`, `let x = T{}`,
`x := T{}`, `T x = ...`, `x: T`, etc.). For Java/Kotlin an import FQN
still pins which same-named class is meant (#314); other languages fall
back to the call-site's own file (#1079).

Ruby is not covered: its extractor emits no `receiver.method()` call
reference in the first place, so there is nothing for resolution to
resolve — a separate extraction-layer gap.

Adds a parameterized end-to-end test covering all twelve languages. Full
suite green.

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

CHANGELOG.md

@@ -9,6 +9,10 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+### New Features
+
+- Method calls made through a local variable now resolve to the method in many more languages. When code does `const logger = new Logger(); logger.log();` (or the equivalent), CodeGraph infers the local variable's type from its declaration or initializer and links the call to the right method — so these calls now show up in callers, impact/blast-radius, and `codegraph_explore` flow traces instead of being dropped. Previously only C++ handled this; it now also covers TypeScript, JavaScript, Python, Java, C#, Kotlin, Swift, Go, Rust, Dart, Scala, and PHP. (#1108)
+
 ### 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)