feat: add worker config reader with secret decryption

worker/lyra_worker/config.py

@@ -0,0 +1,14 @@
+import psycopg
+
+from lyra_worker.crypto import decrypt_secret
+
+
+def get_config(conn: psycopg.Connection) -> dict[str, str]:
+    """Return all config as {key: value}, decrypting rows marked secret."""
+    with conn.cursor() as cur:
+        cur.execute('SELECT key, value, secret FROM "Config"')
+        rows = cur.fetchall()
+    out: dict[str, str] = {}
+    for key, value, secret in rows:
+        out[key] = decrypt_secret(value) if secret else value
+    return out