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/.coveragerc

@@ -0,0 +1,69 @@
+[run]
+# Coverage configuration for Flight Radar Web App
+
+# Source directories
+source = .
+
+# Omit these files from coverage
+omit =
+    */tests/*
+    */test_*.py
+    */__pycache__/*
+    */venv/*
+    */env/*
+    */.venv/*
+    */site-packages/*
+    */dist-packages/*
+    */airports.py
+    */cache.py
+    */cache_admin.py
+    */date_resolver.py
+    */formatter.py
+    */main.py
+    */progress.py
+    */searcher_*.py
+    setup.py
+
+# Include only api_server.py and database files
+include =
+    api_server.py
+    database/*.py
+
+[report]
+# Reporting options
+
+# Precision for coverage percentage
+precision = 2
+
+# Show missing lines
+show_missing = True
+
+# Skip empty files
+skip_empty = True
+
+# Skip covered files
+skip_covered = False
+
+# Exclude lines from coverage
+exclude_lines =
+    # Standard pragma
+    pragma: no cover
+
+    # Don't complain about missing debug code
+    def __repr__
+
+    # Don't complain if tests don't hit defensive assertion code
+    raise AssertionError
+    raise NotImplementedError
+
+    # Don't complain if non-runnable code isn't run
+    if __name__ == .__main__.:
+    if TYPE_CHECKING:
+
+    # Don't complain about abstract methods
+    @abstractmethod
+
+[html]
+# HTML report options
+directory = htmlcov
+title = Flight Radar Web App - Test Coverage Report