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

src/esp32_web/api/devices.py

@@ -0,0 +1,42 @@
+"""Device endpoints."""
+from flask import request
+from . import bp
+from ..models import Device, Sighting
+from ..extensions import db
+
+
+@bp.route('/devices')
+def list_devices():
+    """List all devices."""
+    device_type = request.args.get('type')  # 'ble' or 'wifi'
+    limit = min(int(request.args.get('limit', 100)), 1000)
+    offset = int(request.args.get('offset', 0))
+
+    query = db.select(Device).order_by(Device.last_seen.desc())
+    if device_type:
+        query = query.where(Device.device_type == device_type)
+    query = query.limit(limit).offset(offset)
+
+    devices = db.session.scalars(query).all()
+    return {'devices': [d.to_dict() for d in devices], 'limit': limit, 'offset': offset}
+
+
+@bp.route('/devices/<mac>')
+def get_device(mac):
+    """Get device by MAC."""
+    mac = mac.lower()
+    device = db.session.scalar(db.select(Device).where(Device.mac == mac))
+    if not device:
+        return {'error': 'Device not found'}, 404
+
+    # Include recent sightings
+    sightings = db.session.scalars(
+        db.select(Sighting)
+        .where(Sighting.device_id == device.id)
+        .order_by(Sighting.timestamp.desc())
+        .limit(20)
+    ).all()
+
+    result = device.to_dict()
+    result['sightings'] = [s.to_dict() for s in sightings]
+    return result