Implement drink window alerts system

[fusion94]

Description

Build a system to identify and alert users about wines approaching, within, or past their optimal drink window.

Requirements

Drink Window Logic

Based on drink_from and drink_to fields on wines, calculate status for each bottle:

• Too Young: Current year < drink_from (wine not yet ready)
• Entering Window: drink_from = current year (just became ready this year)
• Ready to Drink: drink_from <= current year <= drink_to (optimal window)
• Approaching Peak End: drink_to - current year <= 1 (last year of window)
• Past Peak: current year > drink_to (past optimal window, still in stock)
• Unknown: drink_from and drink_to are both null (no drink window set)

Backend (covered partially by dashboard stats API)

• Drink window calculation utility function (reusable)
• Filter support: wines can be filtered by drink window status in search
• Alerts API returns wines entering window and past peak

Frontend

• Dashboard alerts widget: Prominent display of wines entering window and past peak
• Drink window badge: Visual indicator on wine cards/list (color-coded)
  • Green: Ready to Drink
  • Yellow: Entering Window / Approaching Peak End
  • Red: Past Peak
  • Gray: Too Young / Unknown
• Wine list filter: Filter by drink window status
• Wine detail display: Show drink window timeline/bar visualization
• Notification dot: Badge on dashboard nav showing alert count

Visual Drink Window Bar

On wine detail page, show a timeline bar:

[===Too Young===|===Ready to Drink===|===Past Peak===]
                    ^ You are here (2026)

Acceptance Criteria

• Drink window status calculated correctly for all scenarios
• Dashboard shows wines entering window and past peak
• Wine cards show drink window badges
• Wine list can be filtered by drink window status
• Wine detail shows visual drink window timeline
• Bottles with no drink window show "Unknown" gracefully
• Alerts count shown on dashboard navigation

References

• PRD Section 3: US-8 (User Stories — approaching optimal drink window)
• PRD Section 4: FR-6 (Drink window alerts in Dashboard)