chore: Enhance CI coverage reporting and add main branch workflow (#4873)

.github/workflows/main-check.yml

@@ -0,0 +1,24 @@
+name: Main CI (Verify & Build)
+
+on:
+  push:
+    branches: [ main ]
+    paths-ignore:
+      - '**/*.md'
+      - 'docs/**'
+
+concurrency:
+  group: main-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  validate-and-build:
+    if: github.repository == 'meshtastic/Meshtastic-Android'
+    uses: ./.github/workflows/reusable-check.yml
+    with:
+      run_lint: true
+      run_unit_tests: true
+      run_instrumented_tests: true
+      api_levels: '[35]' # One API level is enough for post-merge sanity check
+      upload_artifacts: true
+    secrets: inherit