feat(beta): add beta testing features and privacy policy page

Implemented comprehensive beta testing system with tier badges and
reorganized environment configuration for better maintainability.

Beta Testing Features:
- Beta banner component with dismissible state (localStorage)
- Auto-assign SUPPORTER tier to new registrations (env controlled)
- TierBadge component with SUPPORTER/COMFORT tier display
- Badge shown in Navbar, ProfilePage, and PublicProfilePage
- Environment variables: VITE_BETA_MODE, BETA_AUTO_SUPPORTER

Environment Configuration Reorganization:
- Moved .env files from root to frontend/ and backend/ directories
- Created .env.{development,production}{,.example} structure
- Updated docker-compose.yml to use env_file for frontend
- All env vars properly namespaced and documented

Privacy Policy Implementation:
- New /privacy route with dedicated PrivacyPage component
- Comprehensive GDPR/RODO compliant privacy policy (privacy.html)
- Updated CookieConsent banner to link to /privacy
- Added Privacy Policy links to all footers (HomePage, PublicFooter)
- Removed privacy section from About Us page

HTML Content System:
- Replaced react-markdown dependency with simple HTML loader
- New HtmlContentPage component for rendering .html files
- Converted about-us.md and how-it-works.md to .html format
- Inline CSS support for full styling control
- Easier content editing without React knowledge

Backend Changes:
- Registration auto-assigns SUPPORTER tier when BETA_AUTO_SUPPORTER=true
- Added accountTier to auth middleware and user routes
- Updated public profile endpoint to include accountTier

Files:
- Added: frontend/.env.{development,production}{,.example}
- Added: backend/.env variables for BETA_AUTO_SUPPORTER
- Added: components/BetaBanner.jsx, TierBadge.jsx, HtmlContentPage.jsx
- Added: pages/PrivacyPage.jsx
- Added: public/content/{about-us,how-it-works,privacy}.html
- Modified: docker-compose.yml (env_file configuration)
- Modified: App.jsx (privacy route, beta banner)
- Modified: auth.js (auto SUPPORTER tier logic)

frontend/.env.production.example

@@ -0,0 +1,20 @@
+# Frontend - Vite Allowed Hosts
+# Comma-separated list of allowed hostnames
+VITE_ALLOWED_HOSTS=spotlight.cam,.spotlight.cam
+
+# Cloudflare Turnstile (CAPTCHA)
+# Get your keys from: https://dash.cloudflare.com/
+VITE_TURNSTILE_SITE_KEY=your-production-site-key-here
+
+# Google Analytics 4
+# Format: G-XXXXXXXXXX
+# Get your measurement ID from: https://analytics.google.com/
+VITE_GA_MEASUREMENT_ID=
+
+# Beta Testing Features
+# Set to 'true' to show beta banner and enable beta features
+VITE_BETA_MODE=false
+
+# Auto-assign SUPPORTER tier to new registrations during beta
+# Set to 'true' to automatically grant SUPPORTER tier to new users
+VITE_BETA_AUTO_SUPPORTER=false