Harden wellness routine signals

[kanikaa-3018]

Implemented in the wellness hardening branch:

• Reworked wellness from a medical/health-style module into a Routine Signal Index based on spending, meal check-ins,
  runway, spend pace, after-hours payments, and exam dates.

• Removed burnout/stress/medical overclaiming from dashboard, onboarding, and landing page copy.

• Added explicit backend disclaimer: routine score is not medical advice.

• Clarified late-night logic as after-hours payments between 11PM-5AM campus time.

• Added shared backend wellness signal helpers and unit tests.

• Improved meal check-in UX:

  • mess/cooked/home/cash meal sources
  • no fake transaction creation
  • skipped/delayed meal does not reset meal gap
  • save states and duplicate-submit protection
  • context notes for delayed meals

• Connected meal check-ins into dashboard insights, wellness score, campus intelligence, and runway food signals.

• Added exam-period support:

  • Exam Food Checkpoint in Food & Routine
  • meal gap progress/status
  • food target from runway
  • suggested next meal card
  • conditional Log If Ate only when meal signal is stale/missing

• Updated Bedrock prompts to avoid medical inference and only describe budget/routine signals.