chore: move source to repo root and standardize config

Phase 1 — Structural overhaul:
- Move all source from headlamp-sealed-secrets/ subdirectory to repo root
- Delete 23 AI-generated docs, 8 pre-built tarballs, release snapshots dir
- Remove all working-directory refs from CI/release workflows
- Update install-plugin.sh and typedoc.json paths

Phase 2 — Config standardization:
- Create .eslintrc.js and .prettierrc.js (standard Headlamp configs)
- Remove inline eslintConfig/prettier from package.json (drop jsx-a11y, prettier extends)
- Rewrite tsconfig.json (package name extend, add compilerOptions.types)
- Create vitest.config.mts and vitest.setup.ts (standard from polaris)
- Replace headlamp-plugin CLI scripts with direct tool invocation
- Rewrite .gitignore with standard baseline

Phase 3 — MCP & Claude settings:
- Create .mcp.json with github/kubernetes/flux/playwright servers
- Create .claude/settings.local.json
- Remove 7 specialized agents, keep 3 meta-orchestration agents

Phase 4 — Documentation:
- Rewrite CLAUDE.md (remove subdirectory refs, standard format)
- Add ArtifactHub badge, Architecture section, standardized install methods to README.md
- Create CONTRIBUTING.md and SECURITY.md
- Fix pre-existing test bugs in validators.test.ts (isValidNamespace returns boolean,
  not ValidationResult; error message string mismatches)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.mcp.json

@@ -0,0 +1,23 @@
+{
+  "mcpServers": {
+    "github": {
+      "type": "http",
+      "url": "https://api.githubcopilot.com/mcp/",
+      "headers": {
+        "Authorization": "Bearer ${GITHUB_TOKEN}"
+      }
+    },
+    "kubernetes": {
+      "type": "sse",
+      "url": "http://localhost:8080/sse"
+    },
+    "flux": {
+      "type": "sse",
+      "url": "http://localhost:8081/sse"
+    },
+    "playwright": {
+      "type": "sse",
+      "url": "http://localhost:8086/sse"
+    }
+  }
+}