Local dashboard: plain-language status checklist and C2-free listening

- /api/health: ordered checklist (password, C2 approval, MQTT, SDR, source,
  OP25, decoding, audio, Icecast) with what's wrong and what to do; pure
  build_checks() so every state (incl. Toughny's unapproved node) is tested
- /api/listen: pick P25 control channels / one analog freq / a cached C2
  system, validated in MHz, stored as a local override; OP25 restarted with
  the start failure reason surfaced
- /api/config/system no longer writes a raw blob OP25 can't read
- OP25 resumes after reboot on a locally chosen system, not only C2-assigned
- op25-container: analog (NBFM) config generation fixed (AttributeError +
  wrong field names), /op25/log tail, start refuses without a config,
  status detects a dead multi_rx ("crashed") -- node-26#12
- index.html rebuilt on UI_REDESIGN tokens; scanner drops DMR, shows System key

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-edge-node/app/main.py

@@ -327,9 +327,12 @@ async def lifespan(app: FastAPI):
         if (node_cfg.override_system_id and node_cfg.override_config)
         else node_cfg.system_config
     )
-    if node_cfg.configured and active_config:
+    # Not gated on `configured` (set only by a C2 assignment): a standalone or
+    # not-yet-approved node listening to a system chosen on the local
+    # dashboard (an override) must come back on it after a reboot too.
+    if active_config:
         from app.internal.op25_client import op25_client
-        logger.info("Node is configured — waiting for OP25 API then generating config.")
+        logger.info("Node has a system to listen to — waiting for OP25 API then generating config.")
         for attempt in range(10):
             if await _generate_op25_config(active_config):
                 await op25_client.start()