Merge observer firmware branch into keymindCascade

Integrate compatible observer board, preset, WebConfig, display, CI, and policy updates. Preserve the checkout's newer MQTT binary preferences and WiFi bridge runtime where the forked implementations conflict. Keep ThinkNode observer networking WiFi-based until the Ethernet transport is wired into that runtime.

test/test_webconfig_batch/test_webconfig_batch.cpp

@@ -295,6 +295,7 @@ TEST(WebConfigBatch, CliFailureRepliesAreRecognisedInEveryShapeCommonCLIEmits) {
     "Err - bad params",                          // MyMesh setperm
     "ERR: bad pubkey",                           // neighbor.remove
     "Error: IATA code must be exactly 3 letters",// observer setters
+    "Error: setting not persisted; change rolled back", // observer storage failure
     "(ERR: clock cannot go backwards)",          // clock sync, parenthesised
     "Unknown command",                           // top-level fallthrough
     "unknown config: mqtt.nope",                 // set fallthrough