feat: Add photo management features, duplicate detection, attempt limits, and admin deletion

- Add duplicate photo detection (file hash and URL checking)
- Add max attempts per photo with UI counter
- Simplify penalty system (auto-enable when points > 0)
- Prevent scores from going below 0
- Add admin photo deletion functionality
- Improve navigation with always-visible logout
- Prevent users from guessing their own photos

.gitignore

@@ -0,0 +1,52 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/versions
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# env files (can opt-in for committing if needed)
+.env*
+!env.example
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts
+
+/app/generated/prisma
+
+# Uploaded files
+/public/uploads/*
+!/public/uploads/.gitkeep
+
+# Test coverage
+/coverage
+/.nyc_output