fix: fast node creation, first-run modal, simplified docs

- Skip AI calls when no valid OpenAI key (fixes 9-13s timeout)
- Add first-run modal prompting for API key
- Rewrite README for first-time users
- Add /api/health endpoint
- Remove all Anthropic references (not used in OS)
- Fix bootstrap script (dev:local → dev)
- Fix next.config.js devIndicators warning
- Add Node 18+ version check

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/health/route.ts

@@ -0,0 +1,38 @@
+/**
+ * Main health check endpoint
+ * Returns overall system health status for quick verification
+ */
+
+import { NextResponse } from 'next/server';
+import { checkDatabaseHealth } from '@/services/database';
+import { hasValidOpenAiKey } from '@/services/database/descriptionService';
+
+export const runtime = 'nodejs';
+
+export async function GET() {
+  try {
+    const dbHealth = await checkDatabaseHealth();
+
+    const response = {
+      status: dbHealth.connected ? 'ok' : 'degraded',
+      database: dbHealth.connected ? 'connected' : 'disconnected',
+      vectorSearch: dbHealth.vectorExtension ? 'enabled' : 'disabled',
+      aiFeatures: hasValidOpenAiKey() ? 'enabled' : 'disabled (no API key)',
+      timestamp: new Date().toISOString(),
+    };
+
+    return NextResponse.json(response, {
+      status: dbHealth.connected ? 200 : 503,
+    });
+  } catch (error) {
+    return NextResponse.json(
+      {
+        status: 'error',
+        database: 'error',
+        error: error instanceof Error ? error.message : 'Unknown error',
+        timestamp: new Date().toISOString(),
+      },
+      { status: 500 }
+    );
+  }
+}