feat: add smart flight tracking with AviationStack API + visual progress

- Add 20+ flight fields (terminal, gate, delays, estimated times, etc.)
- Smart polling cron with budget-aware priority queue (100 req/month)
- Tracking phases: FAR_OUT → PRE_DEPARTURE → ACTIVE → LANDED
- Visual FlightProgressBar with animated airplane between airports
- FlightCard with status dots, delay badges, expandable details
- FlightList rewrite: card-based, grouped by status, search/filter
- Dashboard: enriched flight status widget with compact progress bars
- CommandCenter: flight alerts + enriched arrivals with gate/terminal

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/tailwind.config.js

@@ -64,6 +64,15 @@ export default {
         md: 'calc(var(--radius) - 2px)',
         sm: 'calc(var(--radius) - 4px)',
       },
+      animation: {
+        'bounce-subtle': 'bounce-subtle 2s ease-in-out infinite',
+      },
+      keyframes: {
+        'bounce-subtle': {
+          '0%, 100%': { transform: 'translateY(0)' },
+          '50%': { transform: 'translateY(-2px)' },
+        },
+      },
     },
   },
   plugins: [],