ci: add MQTT firmware guardrails

.github/workflows/pr-build-check.yml

@@ -5,17 +5,35 @@ on:
     branches: [main, dev]
     paths:
       - 'src/**'
+      - 'include/**'
+      - 'lib/**'
       - 'examples/**'
       - 'variants/**'
+      - 'boards/**'
+      - 'arch/**'
+      - 'scripts/**'
+      - 'ssl_certs/**'
+      - 'webui/**'
+      - 'default_8MB.csv'
       - 'platformio.ini'
+      - '.github/actions/setup-build-environment/**'
       - '.github/workflows/pr-build-check.yml'
   push:
     branches: [main, dev]
     paths:
       - 'src/**'
+      - 'include/**'
+      - 'lib/**'
       - 'examples/**'
       - 'variants/**'
+      - 'boards/**'
+      - 'arch/**'
+      - 'scripts/**'
+      - 'ssl_certs/**'
+      - 'webui/**'
+      - 'default_8MB.csv'
       - 'platformio.ini'
+      - '.github/actions/setup-build-environment/**'
       - '.github/workflows/pr-build-check.yml'
 
 jobs:
@@ -29,6 +47,9 @@ jobs:
           - Heltec_v3_companion_radio_ble
           - Heltec_v3_repeater
           - Heltec_v3_room_server
+          # MQTT observer smoke builds: internal RAM and PSRAM coverage.
+          - Heltec_v3_repeater_observer_mqtt
+          - T_Beam_S3_Supreme_SX1262_repeater_observer_mqtt
           # nRF52
           - RAK_4631_companion_radio_ble
           - RAK_4631_repeater

.github/workflows/run-unit-tests.yml

@@ -19,6 +19,11 @@ jobs:
       - name: Setup Build Environment
         uses: ./.github/actions/setup-build-environment
 
+      - name: Verify ArduinoJson pin
+        run: |
+          python3 -B scripts/check_arduinojson_pin.py --self-test
+          python3 -B scripts/check_arduinojson_pin.py
+
       - name: Run Unit Tests
         run: pio test -e native -vv