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>

vite.config.js

@@ -0,0 +1,28 @@
+import { defineConfig, mergeConfig } from 'vite';
+import baseConfig from '@kinvolk/headlamp-plugin/config/vite.config.mjs';
+
+// Override the base config to add missing externals
+export default mergeConfig(baseConfig, defineConfig({
+  build: {
+    rollupOptions: {
+      output: {
+        globals: (request) => {
+          // Add the missing /lib/lib/k8s/* mappings
+          if (request === '@kinvolk/headlamp-plugin/lib/lib/k8s/cluster') {
+            return 'pluginLib.libk8scluster';
+          }
+          if (request === '@kinvolk/headlamp-plugin/lib/lib/k8s/apiProxy') {
+            return 'pluginLib.libk8sapiProxy';
+          }
+
+          // Use base config's globals function for everything else
+          if (typeof baseConfig.build.rollupOptions.output.globals === 'function') {
+            return baseConfig.build.rollupOptions.output.globals(request);
+          }
+
+          return request;
+        },
+      },
+    },
+  },
+}));