Initial commit — DRB client (edge node) stack

Includes edge-node (FastAPI/MQTT/Discord voice), op25-container (SDR decoder),
and icecast (audio streaming).

drb-edge-node/app/internal/credentials.py

@@ -0,0 +1,39 @@
+"""
+Manages the persisted node API key.
+
+The key is provisioned by the C2 server after an admin approves the node.
+It arrives via MQTT and is saved to /configs/credentials.json so it survives
+container restarts.
+"""
+import json
+from pathlib import Path
+from app.config import settings
+from app.internal.logger import logger
+
+_CREDS_FILE = Path(settings.config_path) / "credentials.json"
+_api_key: str | None = None
+
+
+def load() -> None:
+    """Load persisted credentials from disk on startup."""
+    global _api_key
+    if _CREDS_FILE.exists():
+        try:
+            data = json.loads(_CREDS_FILE.read_text())
+            _api_key = data.get("api_key")
+            if _api_key:
+                logger.info("Node credentials loaded from disk.")
+        except Exception as e:
+            logger.warning(f"Could not read credentials file: {e}")
+
+
+def get_api_key() -> str | None:
+    return _api_key
+
+
+def save_api_key(key: str) -> None:
+    global _api_key
+    _api_key = key
+    _CREDS_FILE.parent.mkdir(parents=True, exist_ok=True)
+    _CREDS_FILE.write_text(json.dumps({"api_key": key}))
+    logger.info("Node API key saved to disk.")