Feature/bedrock intelligence hardening

[kanikaa-3018]

What changed:

• Tightened campus-intel grounding so Bedrock cannot invent plain counts like commitment totals.

• Fixed date parsing in rag.py to normalize timezone-aware timestamps correctly before campus-intel logic uses them.

• Limited food-gap signals to debit food transactions only, so the wellness/food nudges stay cleaner.

• Hardened travel AI coach end to end:

  • validates script, tactics, and safety text against backend-owned fare facts
  • blocks invented fares, live-app/live-traffic style claims, and unsupported safety claims
  • falls back cleanly to deterministic local guidance when Bedrock drifts or fails

• Improved travel fallback safety copy so it stays actionable instead of showing vague labels.

• Added regression tests for:

  • exact plain-number grounding
  • travel AI fallback on invented fare output
  • grounded travel AI success path
  • actionable travel safety fallback