Add flight comparator web app with full scan pipeline

Full-stack flight price scanner built on fast-flights v3 (SOCS cookie bypass):

Backend (FastAPI + SQLite):
- REST API with rate limiting, Pydantic v2 validation, paginated responses
- Scan pipeline: resolves airports, queries every day in the window, saves
  individual flights + aggregate route stats to SQLite
- Background async scan processor with real-time progress tracking
- Airport search endpoint backed by OpenFlights dataset
- Daily scan window (all dates, not monthly samples)

Frontend (React 19 + TypeScript + Tailwind CSS v4):
- Dashboard with live scan status and recent scans
- Create scan form: country mode or specific airports (searchable dropdown)
- Scan detail page with expandable route rows showing individual flights
  (date, airline, departure, arrival, price) loaded on demand
- AirportSearch component with debounced live search and multi-select

Database:
- scans → routes → flights schema with FK cascade and auto-update triggers
- Migrations for schema evolution (relaxed country constraint)

Tests:
- 74 tests: unit + integration, isolated per-test SQLite DB
- Confirmed flight fixtures in tests/confirmed_flights.json (50 real flights,
  BDS→FMM Ryanair + BDS→DUS Eurowings, scraped Feb 2026)
- Integration tests parametrized from confirmed routes

Docker:
- Multi-stage builds, Compose orchestration, Nginx reverse proxy

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

flight-comparator/frontend/src/index.css

@@ -0,0 +1,18 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+@keyframes slide-up {
+  from {
+    transform: translateY(100%);
+    opacity: 0;
+  }
+  to {
+    transform: translateY(0);
+    opacity: 1;
+  }
+}
+
+.animate-slide-up {
+  animation: slide-up 0.3s ease-out;
+}