[codex] Clamp numeric query parameters

[pq198363-ops]

Closes #91

Summary

• Added a shared parseIntParam helper for defensive numeric query parsing.
• Applied bounded fallback/clamp behavior to limit and since handling on the affected list endpoints:
  • GET /api/v1/events
  • GET /api/v1/agents
  • GET /api/v1/services
  • GET /api/v1/services/:serviceId/agents/top
• Documented the query parameter defaults and supported ranges in the README.

Validation

RED evidence:

• The focused query-parameter test initially failed at build time because src/queryParams.ts did not exist yet.

GREEN evidence:

• npx prettier --check README.md src/queryParams.ts src/query-params.test.ts src/routes/events.ts src/routes/services.ts src/routes/usage.ts
• npm run lint
• git diff --check
• Cleaned dist/, then ran npm run build
• Windows test command: $env:NODE_ENV='test'; node --test dist/*.test.js dist/**/*.test.js

Result: full test run passed, 93 tests across 11 suites.

Notes

Malformed, empty, NaN, or infinite numeric query values now fall back to the endpoint default. Out-of-range finite values are clamped so bad input cannot propagate NaN into slices or timestamp filters.