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>

src/components/LoadingSkeletons.tsx

@@ -0,0 +1,111 @@
+/**
+ * Loading Skeleton Components
+ *
+ * Provides visual feedback during data loading with skeleton screens
+ * to improve perceived performance and user experience.
+ */
+
+import { Box, Skeleton } from '@mui/material';
+import React from 'react';
+
+/**
+ * Skeleton for SealedSecrets list view
+ *
+ * Shows placeholder rows while data is loading
+ */
+export function SealedSecretListSkeleton() {
+  return (
+    <Box p={2}>
+      {[1, 2, 3, 4, 5].map(i => (
+        <Skeleton
+          key={i}
+          variant="rectangular"
+          height={60}
+          sx={{ mb: 1, borderRadius: 1 }}
+          animation="wave"
+        />
+      ))}
+    </Box>
+  );
+}
+
+/**
+ * Skeleton for SealedSecret detail view
+ *
+ * Shows placeholder sections while resource is loading
+ */
+export function SealedSecretDetailSkeleton() {
+  return (
+    <Box p={3}>
+      {/* Title */}
+      <Skeleton variant="text" width="40%" height={40} sx={{ mb: 3 }} animation="wave" />
+
+      {/* Metadata section */}
+      <Skeleton variant="rectangular" height={200} sx={{ mb: 2, borderRadius: 1 }} animation="wave" />
+
+      {/* Encrypted data section */}
+      <Skeleton variant="rectangular" height={150} sx={{ mb: 2, borderRadius: 1 }} animation="wave" />
+
+      {/* Actions section */}
+      <Box sx={{ display: 'flex', gap: 2 }}>
+        <Skeleton variant="rectangular" width={120} height={36} sx={{ borderRadius: 1 }} animation="wave" />
+        <Skeleton variant="rectangular" width={120} height={36} sx={{ borderRadius: 1 }} animation="wave" />
+      </Box>
+    </Box>
+  );
+}
+
+/**
+ * Skeleton for sealing keys list view
+ *
+ * Shows placeholder for certificate information
+ */
+export function SealingKeysListSkeleton() {
+  return (
+    <Box p={2}>
+      {[1, 2].map(i => (
+        <Box key={i} sx={{ mb: 3 }}>
+          <Skeleton variant="text" width="30%" height={32} sx={{ mb: 1 }} animation="wave" />
+          <Skeleton variant="rectangular" height={100} sx={{ borderRadius: 1, mb: 1 }} animation="wave" />
+          <Box sx={{ display: 'flex', gap: 1 }}>
+            <Skeleton variant="rectangular" width={100} height={28} sx={{ borderRadius: 1 }} animation="wave" />
+            <Skeleton variant="rectangular" width={100} height={28} sx={{ borderRadius: 1 }} animation="wave" />
+          </Box>
+        </Box>
+      ))}
+    </Box>
+  );
+}
+
+/**
+ * Skeleton for certificate information
+ *
+ * Shows placeholder for certificate metadata
+ */
+export function CertificateInfoSkeleton() {
+  return (
+    <Box>
+      <Skeleton variant="text" width="60%" animation="wave" />
+      <Skeleton variant="text" width="40%" animation="wave" />
+      <Skeleton variant="text" width="50%" animation="wave" />
+      <Skeleton variant="text" width="45%" animation="wave" />
+    </Box>
+  );
+}
+
+/**
+ * Skeleton for controller health status
+ *
+ * Shows placeholder for health check information
+ */
+export function ControllerHealthSkeleton() {
+  return (
+    <Box sx={{ display: 'flex', alignItems: 'center', gap: 2 }}>
+      <Skeleton variant="circular" width={40} height={40} animation="wave" />
+      <Box sx={{ flex: 1 }}>
+        <Skeleton variant="text" width="40%" animation="wave" />
+        <Skeleton variant="text" width="60%" animation="wave" />
+      </Box>
+    </Box>
+  );
+}