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/config.py

@@ -0,0 +1,25 @@
+"""Application configuration."""
+import os
+
+
+class Config:
+    """Base configuration."""
+    SECRET_KEY = os.environ.get('SECRET_KEY', 'dev-key-change-me')
+    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL', 'sqlite:///esp32.db')
+    SQLALCHEMY_TRACK_MODIFICATIONS = False
+
+    # Network
+    UDP_LISTEN_PORT = int(os.environ.get('UDP_PORT', 5500))
+    SENSOR_CMD_PORT = int(os.environ.get('CMD_PORT', 5501))
+    SENSOR_TIMEOUT = int(os.environ.get('SENSOR_TIMEOUT', 60))
+
+
+class TestConfig(Config):
+    """Testing configuration."""
+    TESTING = True
+    SQLALCHEMY_DATABASE_URI = 'sqlite:///:memory:'
+
+
+class ProdConfig(Config):
+    """Production configuration."""
+    pass