Use self-hosted runner for ESP-Matter builds

Workflow:
- Switch esp-matter-build job to self-hosted runner
- Use [self-hosted, ubuntu-latest] for runner selection
- Prevents 'No space left on device' errors on GitHub-hosted runners
- ESP-Matter builds require ~50GB+ due to large submodule tree

Documentation:
- Add 'Self-Hosted Runners' section to github-actions-standards.mdc
- Document when to use self-hosted runners (large submodules, disk space)
- Document runner requirements (Docker, Buildx, 50GB+ free space)

Author: hacker-cb

.cursor/rules/github-actions-standards.mdc

@@ -198,6 +198,27 @@ jobs:
 - Login condition: `if: github.repository_owner == 'jethome-iot' && github.ref_name == 'master'`
 - Push condition: `push: ${{ github.repository_owner == 'jethome-iot' && github.ref_name == 'master' }}`
 
+### Self-Hosted Runners
+
+For large builds that may exceed GitHub-hosted runner disk space (e.g., ESP-Matter with large submodule trees), use self-hosted runners:
+
+```yaml
+jobs:
+  <image-name>-build:
+    runs-on: [self-hosted, ubuntu-latest]  # Use self-hosted runner
+    timeout-minutes: 60
+```
+
+**When to use self-hosted runners:**
+- Builds with large git submodules (ESP-Matter, etc.)
+- Builds that consistently fail with "No space left on device"
+- Builds requiring more than ~14GB disk space
+
+**Runner requirements:**
+- Docker and Docker Buildx installed
+- Sufficient disk space (50GB+ free recommended for large builds)
+- Runner labels: `self-hosted`, `ubuntu-latest` (or appropriate OS label)
+
 ### Version Handling
 
 - Define versions directly in matrix strategy

.github/workflows/esp-idf.yml

@@ -78,7 +78,7 @@ jobs:
             IDF_BASE_TAG=${{ matrix.idf_base_tag }}
 
   esp-matter-build:
-    runs-on: ubuntu-latest
+    runs-on: [self-hosted, ubuntu-latest]
     timeout-minutes: 60
     needs: esp-idf-build
     if: github.repository_owner == 'jethome-iot' || github.event_name == 'workflow_dispatch'