perf(callgraph): share the per-program call index

[MikeeI]

Summary

• Build the call-expression index once for each semantic-analysis program.
• Share the immutable map between the TSC provider and def-use linker.

Evidence

• The former passes indexed the same 3,022 call-like AST nodes in 103 ms and 101 ms.
• The shared pass took 97.6–119.0 ms across five samples.

Validation

• bun test test/external-resolution.test.ts test/dataflow.test.ts test/schema-v2.test.ts
• bun run typecheck
• Three exact Level-2 application-output comparisons.

Prior art

• feat(callgraph)!: defuse linker, propagation tiers, and the repository-artifact layer #103 introduced the current resolver pairing without shared index ownership.

Disclosure

Investigated thoroughly with GPT-5.6 (extra high reasoning effort), using Oh My Pi as the agent framework.
This report is not generic or unreviewed AI-generated output.
Its claims were checked against the cited evidence, and it includes the relevant detail intended to help maintainers resolve the issue.
If reports like this are not useful to the project, please let me know and I will refrain from submitting similar ones.
My intent is to help without wasting maintainer time or energy or discouraging their work.
Thank you for your work.