fix: add markdownlint config and auto-fix markdown errors

- Add .markdownlint-cli2.jsonc based on headlamp-agent-skills config
- Disable MD013 (line length), MD041 (first-line-heading), MD036
  (emphasis-as-heading), MD024 (no-duplicate-heading), MD040
  (fenced-code-language), MD060 (table-column-style), MD029
  (ol-prefix), MD033 (no-inline-html) — appropriate for plugin docs
- Run markdownlint-cli2 --fix to auto-fix MD022, MD031, MD032
- Manually fix remaining code block language annotations

Co-Authored-By: Paperclip <noreply@paperclip.ing>

CLAUDE.md

@@ -33,7 +33,7 @@ All tests and `tsc` must pass before committing.
 
 ## Architecture
 
-```
+```text
 src/
 ├── index.tsx                           # Plugin entry: registerRoute, registerSidebarEntry, registerDetailsViewSection, registerAppBarAction, registerPluginSettings; PolarisErrorBoundary
 ├── test-utils.tsx                      # Shared test fixtures (makeResult, makeAuditData)
@@ -73,9 +73,10 @@ Data is fetched via `ApiProxy.request` to the Polaris dashboard service proxy an
 ## Testing
 
 Mock pattern for headlamp APIs:
+
 ```typescript
 vi.mock('@kinvolk/headlamp-plugin/lib', () => ({
   ApiProxy: { request: vi.fn().mockResolvedValue({}) },
   K8s: { ResourceClasses: {} },
 }));
-```
+```