fix: tolerate untimestamped trace type data

[jianmosier]

Summary

• allow stock TypeScript types.json entries without ts timestamps to parse safely
• expose trace data summary counts for total, timestamped, and untimestamped type entries
• keep timestamped type attribution for trace-tree spans while avoiding false attribution for untimestamped stock data

Validation

• pnpm exec vitest run test/traceData.test.ts test/traceTree.test.ts
• pnpm typecheck

Scope

Draft PR for parser/tree correctness only. It does not touch hot-path visualization, virtualization, depth-limit highlighting, Windows cwd/drive behavior, or trace-server work.