ci(workflow): Enhance quality gate, streamline validation, and add AI guidance

- **Quality Gate (.github/workflows/quality-gate.yml):**
- Expanded push triggers to include main, release/**, and feature/** branches.
- Added concurrency control to cancel in-progress runs, preventing redundant checks.
- Refined workflow permissions to be more specific (contents: read, pull-requests: write, issues: write), enhancing security.
- **Local Validation (validate.sh):**
- Removed the validate.sh script, as its checks are now integrated into or superseded by the CI pipeline.
- **AI Guidance (CLAUDE.md):**
- Introduced CLAUDE.md to provide comprehensive guidance for Claude Code, detailing project architecture, commands, and conventions for AI assistants.
- **SonarQube Configuration (sonar-project.properties):**
- Removed hardcoded sonar.projectVersion.

sonar-project.properties

@@ -7,5 +7,4 @@ sonar.qualitygate.timeout=300
 sonar.python.coverage.reportPaths=coverage.xml
 sonar.python.xunit.reportPath=pytest.xml
 sonar.python.version=3.11
-sonar.projectVersion=1.2.0
 sonar.coverage.exclusions=ingestor/app.py