Remove all E2E infrastructure — approach is dead

Delete the entire local E2E testing setup:
- e2e/ directory (Playwright tests)
- scripts/deploy-e2e-headlamp.sh and teardown-e2e-headlamp.sh
- .github/workflows/e2e.yaml
- deployment/ (RBAC files and PLUGIN_LOADING_FIX.md)
- playwright.config.ts
- E2E npm scripts and @playwright/test dependency
- E2E-related .gitignore entries

RBAC is managed by Flux GitOps in privilegedescalation/infra.

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

.gitignore

@@ -2,10 +2,6 @@ node_modules/
 dist/
 .headlamp-plugin/
 *.tar.gz
-e2e/.auth/
-test-results/
-.playwright-mcp/
 .env
-.env.e2e
 .env.local
 .eslintcache