Suppress noisy trace diagnostics

[liurenfeng94-ops]

Fixes #50

This trims trace diagnostics that are not useful to act on: declaration files and type-only declarations. The goal is to keep the trace warnings focused on source locations where a code change can actually help, while still leaving value-level trace diagnostics intact.

Validation:

• pnpm vitest run test/trace-diagnostic-filter.test.ts
• pnpm vitest run
• pnpm typecheck
• pnpm exec eslint .
• pnpm build

[github-actions]

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[liurenfeng94-ops]

Thanks — I rewrote the description to spell out the actual behavior change. The code now skips declaration-file noise and type-only declarations, so the diagnostics stay on source edits that can be acted on.