feat(temporal): Go in-workflow query/signal/update handlers + env-default dispatch names

[avfirsov]

Summary

Two small, independent additions to the Temporal Go extractor/resolver, each mirroring an existing pattern in the codebase. They close two gaps in the Go-side Temporal surface; the larger cross-language Java→Go bridge is proposed separately for design discussion in #77 (not in this PR).

The two commits are independent and can be reviewed / merged / split separately.

Changes

1. Detect in-workflow query/signal/update handler declarations (feat(temporal): detect Go in-workflow query/signal/update handler declarations)

• Recognises workflow.SetQueryHandler / GetSignalChannel / SetUpdateHandler[WithOptions] and emits a via=temporal.handler EdgeCalls edge from the enclosing workflow carrying temporal_kind (query/signal/update) + temporal_name.
• Mirrors the existing via=temporal.register / via=temporal.stub emission exactly, and gives the graph a symmetric, queryable record of the named handlers a Go workflow exposes — the Go counterpart to the Java side's @QueryMethod / @SignalMethod / @UpdateMethod annotation edges.
• High-precision: only the canonical workflow receiver alias matches and the handler name must be a string literal (runtime-matched names can't be pinned from a variable), consistent with the existing dispatch detector.

2. Resolve activity/workflow names from env-var-with-default variables (feat(temporal): resolve activity/workflow names from env-var-with-default vars)

• When a dispatch name is a local variable read from an env var with a literal fallback, resolves the call to that literal default instead of leaving it unresolved:

  actName := cmp.Or(os.Getenv("CHARGE_ACTIVITY"), "ChargeCard")
  workflow.ExecuteActivity(ctx, actName, id)   // → activity "ChargeCard"
  
  name := os.Getenv("K"); if name == "" { name = "ChargeCard" }

• The lookup is narrow and intra-procedural, anchored on a literal os.Getenv / os.LookupEnv read (so the value is provably env-sourced — not general constant propagation), and only considers assignments lexically before the call.
• The resolved edge lands at the speculative tier (OriginSpeculative, confidence 0.4, MetaSpeculative=true) rather than ast_resolved — the runtime env override may name a different handler than the literal default, so the edge is present but hidden from default queries, reusing the existing speculative-edge convention.

Testing

• All tests pass (go test -race ./...) — for the touched packages (internal/parser/languages, internal/resolver, internal/indexer temporal suites). The only failures in my environment are the internal/indexer watcher tests failing with inotify ... too many open files (a WSL fd-limit issue, unrelated — no watcher files are touched).
• New tests added for new functionality — parser-level (go_temporal_test.go), resolver-level (temporal_calls_test.go), and end-to-end (temporal_e2e_test.go) for both features, including negative cases (non-literal handler name, plain non-env variable, env read with no literal default, unresolved-stays-placeholder).
• Benchmarks run if performance-relevant — both passes are AST-local / reuse existing graph walks; no new whole-graph scans.

Checklist

• Code follows existing patterns in the codebase (mirrors applyGoTemporalRegisterMeta, the speculative-dispatch tier, the existing detector's high-precision stance)
• No unnecessary abstractions added
• Language extractor includes Meta["methods"] for interfaces (if applicable) — n/a, no interface extraction changed
• Methods have EdgeMemberOf edges to their containing type (if applicable) — n/a

Notes for reviewers

• Both features are deliberately scoped to the Go side only. The cross-language join (linking a Java @WorkflowInterface start to the Go workflow / a Java @QueryMethod to the Go SetQueryHandler provider added here) raises edge-model and confidence-tier design questions, so it's filed as Cross-language Java→Go Temporal linking (starts_temporal_workflow by canonical name) #77 rather than bundled here.
• The aliased-import limitation (only the canonical workflow receiver is matched) is preserved and pinned by a test, consistent with the existing dispatch detector.

[avfirsov]

Split into two focused PRs so each can be reviewed/merged independently:

• feat(temporal): detect Go in-workflow query/signal/update handler declarations #78 — Go in-workflow query/signal/update handler edges (via=temporal.handler)
• feat(temporal): resolve activity/workflow dispatch names from env-var-with-default vars #79 — env-var-with-default dispatch name resolution (speculative tier)

Closing this combined PR in favour of those two.