fix(core-agent): keep near-duplicate detection warn-only

[CloudTianTian]

Summary

• keep normalized near-duplicate tool-call detection as a one-time warning
• avoid terminating valid work solely because volatile request ids or timestamps were ignored by the fuzzy signature
• retain hard stops for byte-identical repeats, the independent no-progress governor, and the configured tool-round limit

Testing

• node scripts/run-tests.mjs run src/core-agent/test/agent-runner.test.ts src/core-agent/test/near-dup-loop.test.ts — 113 passed
• node scripts/run-tests.mjs run src/core-agent/test — 32 files / 678 tests passed
• npm run typecheck — passed
• git diff --check and removed-symbol residue check — passed

The repository-wide npm test baseline is not clean in this environment: unmodified origin/main reproduces an EACCES failure for /Users/userWorkSpace in the video script fixture and a local OfficeCLI binary hash mismatch. Neither path is touched here.