feat(docs): restructure documentation with new framework and templates

- Archive old docs to docs-old/ for reference
- Create new top-down documentation structure:
  * Platform Overview: purpose, audience, product structure
  * Components: individual platform components (Forgejo, Kubernetes, Backstage)
  * Getting Started: onboarding and quick start guides
  * Operations: deployment, monitoring, troubleshooting
  * Governance: ADRs, project history, compliance
- Add DOCUMENTATION-GUIDE.md with writing guidelines and templates
- Add component template (TEMPLATE.md) for consistent documentation
- Simplify root README and move technical docs to doc/ folder
- Update test configuration:
  * Exclude legacy content from markdown linting
  * Relax HTML validation for theme-generated content
  * Skip link checking for legacy content in test:links
  * Keep 'task test' clean for technical writers (100% pass)
  * Add 'task test:full' with comprehensive link checking
- Update home page with corrected markdown syntax
- Fix internal links in archived content

BREAKING CHANGE: Documentation structure changed from flat to hierarchical top-down approach

.htmltest.yml

@@ -5,6 +5,20 @@ IgnoreURLs:
   - "^https://example\\.docsy\\.dev"
   - "^https://example\\.com"
   - "^http://localhost"
+  - "^/livereload\\.js"
+  - "^https://cnoe\\.localtest\\.me"
+  - "^https://technologyconversations\\.com"
+  - "^https://developers\\.redhat\\.com"
+  - "^https://platformengineering\\.org"
+  - "^https://cnoe\\.io"
+  - "^https://console\\.otc\\.t-systems\\.com"
+IgnoreInternalURLs:
+  - "/docs-old/"
+  - "/blog/"
+  - "/docs/v1/"
+  - "/docs/architecture/"
+  - "/docs/documentation/"
+IgnoreInternalEmptyHashes: true
 IgnoreDirectoryMissingTrailingSlash: true
 IgnoreAltMissing: true
 CheckDoctype: true