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- Removed the validate.sh script, as its checks are now integrated into or superseded by the CI pipeline.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.

.github/workflows/quality-gate.yml

@@ -1,6 +1,11 @@
 name: Quality gate
 
 on:
+  push:
+    branches:
+      - main
+      - 'release/**'
+      - 'feature/**'
   pull_request:
     branches:
       - main
@@ -8,10 +13,17 @@ on:
       - 'feature/**'
     types: [ opened, synchronize, reopened ]
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   quality-gate:
     uses: Aignosi/github_workflow_templates/.github/workflows/python-quality-gate.yml@main
-    permissions: write-all
+    permissions:
+      contents: read
+      pull-requests: write
+      issues: write
     with:
       project_name: 'ingestor'
       repositories: 'sientia-dataops-library'