fix: add web app deps and git to Docker build

- Added fastapi, uvicorn, pydantic, requests to requirements.txt
  (were missing — only CLI deps were present)
- Changed fast-flights entry to git+GitHub URL (v3 not on PyPI)
- Added git to apt-get install in Dockerfile (needed for pip git+ URL)

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

flight-comparator/requirements.txt

@@ -1,4 +1,15 @@
+# Web API
+fastapi>=0.104.0
+uvicorn[standard]>=0.24.0
+pydantic>=2.0.0
+
+# CLI tool
 click>=8.0.0
 python-dateutil>=2.8.0
 rich>=13.0.0
-fast-flights>=3.0.0
+
+# Shared utilities
+requests>=2.31.0
+
+# Flight search (GitHub only — not on PyPI as a stable release)
+git+https://github.com/AWeirdDev/flights.git