feat: extract business logic into custom React hooks (Phase 3.1)

Refactor components to use custom hooks for business logic, dramatically
simplifying component code while improving testability and reusability.

Changes:
- Create useSealedSecretEncryption() hook
  - Encapsulates complete encryption workflow
  - Handles validation, cert fetching, expiry checks, encryption
  - Built-in error handling with snackbar notifications
  - Returns ready-to-apply SealedSecret object
  - Type-safe Result<T, E> pattern

- Create useControllerHealth() hook
  - Encapsulates health monitoring logic
  - Auto-refresh with configurable interval
  - Manual refresh function
  - Loading state management
  - Proper cleanup

- Refactor EncryptDialog component
  - Simplified from 215 → 130 lines (-85 lines, -40%)
  - Business logic extracted to hook
  - Focus on presentation logic only
  - Much easier to understand and maintain

- Refactor ControllerStatus component
  - Simplified from 115 → 58 lines (-57 lines, -50%)
  - One-line hook usage
  - Perfect abstraction example

Benefits:
- Separation of concerns (business vs presentation)
- Reusable hooks across components
- Easier to test (hooks testable independently)
- Better maintainability (single source of truth)
- Code reduction: ~140 lines removed from components

Build: 352.05 kB (96.99 kB gzipped), +0.71 kB (+0.2%)
Phase 3.1 complete. 8 of 14 phases done (57%).

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

headlamp-sealed-secrets/src/components/ControllerStatus.tsx

@@ -8,7 +8,7 @@
 import { CheckCircle, Error as ErrorIcon, Warning } from '@mui/icons-material';
 import { Box, Chip, CircularProgress, Tooltip, Typography } from '@mui/material';
 import React from 'react';
-import { checkControllerHealth, ControllerHealthStatus, getPluginConfig } from '../lib/controller';
+import { useControllerHealth } from '../hooks/useControllerHealth';
 
 interface ControllerStatusProps {
   /** Whether to auto-refresh the status */
@@ -27,32 +27,7 @@ export function ControllerStatus({
   refreshIntervalMs = 30000,
   showDetails = true,
 }: ControllerStatusProps) {
-  const [status, setStatus] = React.useState<ControllerHealthStatus | null>(null);
-  const [loading, setLoading] = React.useState(true);
-
-  const fetchStatus = React.useCallback(async () => {
-    setLoading(true);
-    const config = getPluginConfig();
-    const result = await checkControllerHealth(config);
-
-    if (result.ok) {
-      setStatus(result.value);
-    }
-    setLoading(false);
-  }, []);
-
-  // Initial fetch
-  React.useEffect(() => {
-    fetchStatus();
-  }, [fetchStatus]);
-
-  // Auto-refresh
-  React.useEffect(() => {
-    if (!autoRefresh) return;
-
-    const interval = setInterval(fetchStatus, refreshIntervalMs);
-    return () => clearInterval(interval);
-  }, [autoRefresh, refreshIntervalMs, fetchStatus]);
+  const { health: status, loading } = useControllerHealth(autoRefresh, refreshIntervalMs);
 
   if (loading || !status) {
     return (