Fix: replace non-existent apps with real templates, fix 500 errors on old doc paths

- AppShowcase: Removed 7 non-existent apps (Kaleidescape, Synology Photos, Homelabs, DockSTARTer, Unraid, TrueNAS, New Relic), added 50+ real app templates that exist in code
- Updated template count from 76+ to 92+ across all pages
- Fixed test count from 1400+ to 775+ (actual count)
- Added mod_rewrite fallback for old doc path redirects (fixes 500 errors)
- Added caching, compression, and proper error handling in .htaccess

src/app/docs/premium/page.tsx

@@ -39,7 +39,7 @@ export default function DocsPremiumPage() {
           </thead>
           <tbody>
             <tr><td>Dashboard &amp; web UI</td><td>✓</td><td>✓</td></tr>
-            <tr><td>76+ application templates</td><td>✓</td><td>✓</td></tr>
+            <tr><td>92+ application templates</td><td>✓</td><td>✓</td></tr>
             <tr><td>Caddy reverse proxy + auto HTTPS</td><td>✓</td><td>✓</td></tr>
             <tr><td>Caddyfile-as-Code builder</td><td>✓</td><td>✓</td></tr>
             <tr><td>Technitium DNS automation</td><td>✓</td><td>✓</td></tr>