fix: tech debt batch 1 — TS errors, vulnerabilities, dead code

- Fixed 12 TypeScript errors across analytics.ts, observer-project-detail.tsx, bulk-upload/page.tsx, settings/profile/page.tsx
- npm audit: 8 vulnerabilities resolved (1 critical, 4 high, 3 moderate)
- Deleted 3 dead files: live-control.ts (618 lines), feature-flags.ts, file-type-categories.ts
- Removed typescript.ignoreBuildErrors: true — TS errors now block builds

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

src/app/(admin)/admin/projects/bulk-upload/page.tsx

@@ -1,6 +1,7 @@
 'use client'
 
 import { useState, useCallback, useRef, useEffect, useMemo } from 'react'
+import Link from 'next/link'
 import { useRouter } from 'next/navigation'
 import { trpc } from '@/lib/trpc/client'
 import { toast } from 'sonner'