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

tests/conftest.py

@@ -0,0 +1,28 @@
+"""Pytest fixtures."""
+import pytest
+from esp32_web import create_app
+from esp32_web.extensions import db
+from esp32_web.config import TestConfig
+
+
+@pytest.fixture
+def app():
+    """Create test application."""
+    app = create_app(TestConfig)
+    with app.app_context():
+        db.create_all()
+        yield app
+        db.drop_all()
+
+
+@pytest.fixture
+def client(app):
+    """Create test client."""
+    return app.test_client()
+
+
+@pytest.fixture
+def db_session(app):
+    """Database session for tests."""
+    with app.app_context():
+        yield db.session