perf(dataflow): scan throwability once per statement

[MikeeI]

Summary

• Detect the existing four throw-capable syntax kinds in one subtree traversal.
• Preserve root inspection and nested function and class boundaries.

Evidence

• Four-scan samples took 79.5–116.7 ms with a 102.2 ms median.
• One-scan samples took 43.5–57.0 ms with a 52.1 ms median and identical booleans.

Validation

• bun test test/dataflow.test.ts
• bun run typecheck
• Exact mayThrow comparison for all 5,965 self-analysis statements.

Prior art

• L3/L4 populate 0.7% of callables on multi-program repos — dataflow uses one root tsconfig #111 and Scaling L1-L4 past vscode: three memory ceilings and a sequenced path #112 cover broader dataflow scaling but do not identify this local repeated traversal.

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.