🤖 feat: implement trunk-based CI/CD with local testing

- Designed trunk-based development workflow with branch protection
- Added workflow validation job to prevent main branch breaks
- Integrated act (GitHub Actions runner) for local Gitea workflow testing
- Created unified CI/CD script interface (scripts/cicd.sh)
- Added YAML lint configuration with practical limits (400 chars)
- Organized all CI/CD scripts under scripts/cicd/ directory
- Confirmed Gitea/GitHub Actions compatibility via local testing
- Updated ADR 0017 with implementation details and test results
- Enhanced documentation with local development workflow

See ADR-0017 for complete trunk-based development workflow documentation.
See ADR-0016 for CI/CD pipeline design.

config/runner.example

@@ -0,0 +1,25 @@
+# Gitea Runner Configuration Example
+# This file should be copied to config/runner and filled with actual values
+# The config/runner file should be gitignored
+
+# Runner configuration format:
+# {
+#   "id": 1,
+#   "uuid": "runner-uuid-here",
+#   "name": "local-test-runner",
+#   "token": "registration-token-here",
+#   "labels": ["ubuntu-latest", "docker"],
+#   "runner_type": "act"
+# }
+
+# To generate this file:
+# 1. Go to your Gitea instance: https://gitea.arcodange.lab/arcodange/DanceLessonsCoach/settings/actions/runners
+# 2. Create a new runner
+# 3. Download the configuration
+# 4. Save it as config/runner
+
+# Environment variables for docker-compose:
+# GITEA_INSTANCE_URL=https://gitea.arcodange.lab/
+# GITEA_RUNNER_REGISTRATION_TOKEN=your-registration-token
+# GITEA_RUNNER_NAME=local-test-runner
+# GITEA_RUNNER_LABELS=ubuntu-latest:docker://node:16-bullseye,ubuntu-22.04:docker://gitea/act_runner:latest