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

Containerfile

@@ -0,0 +1,18 @@
+FROM python:3.12-slim
+
+WORKDIR /app
+
+# Install dependencies
+COPY pyproject.toml .
+RUN pip install --no-cache-dir .
+
+# Copy source
+COPY src/ src/
+COPY migrations/ migrations/
+
+# Expose ports (TCP for HTTP, UDP for collector)
+EXPOSE 5500/tcp
+EXPOSE 5500/udp
+
+# Run with gunicorn
+CMD ["gunicorn", "-b", "0.0.0.0:5500", "esp32_web:create_app()"]