feat: Initial project scaffold

Flask API backend for ESP32 sensor fleet:
- App factory pattern with blueprints
- SQLAlchemy 2.x models (Sensor, Device, Sighting, Alert, Event, Probe)
- UDP collector for sensor data streams
- REST API endpoints for sensors, devices, alerts, events, probes, stats
- pytest setup with fixtures
- Containerfile for podman deployment
- Makefile for common tasks

.gitignore

@@ -0,0 +1,37 @@
+# Python
+__pycache__/
+*.py[cod]
+*.so
+*.egg
+*.egg-info/
+dist/
+build/
+.eggs/
+
+# Virtual environments
+.venv/
+venv/
+ENV/
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# Testing
+.pytest_cache/
+.coverage
+htmlcov/
+.tox/
+
+# Flask
+instance/
+*.db
+
+# Environment
+.env
+.env.local
+
+# Ruff
+.ruff_cache/