feat: DNS provider abstraction — Technitium, Cloudflare, RFC 2136, Manual

- dns-providers/: adapter base class + registry with auto-discovery
- technitium.js: wraps existing Technitium API calls into adapter interface
- cloudflare.js: Cloudflare API v4 adapter (zones, records, credentials)
- rfc2136.js: RFC 2136 dynamic DNS via nsupdate (BIND, PowerDNS, etc.)
- manual.js: no-op adapter for external DNS management with instructions
- provider-dns.js: provider-aware DNS context, resolves active adapter from config
- Universal helper methods: universalCreateRecord/Delete/ResolveRecord
- All 7 route files updated to use universal methods instead of raw dns.call()
- Setup wizard: provider dropdown (Technitium, Cloudflare, RFC 2136, Manual)
- DNS template selector: added Cloudflare and External/Manual options
- Config schema: validates dns.provider field
- Capability gating on Technitium-specific endpoints (logs, restart, update)
- Backward compatible: no provider set = auto-detect (technitium if dns.ip exists)

status/js/dns-template-selector.js

@@ -95,6 +95,36 @@
             'Prometheus metrics'
           ],
           recommended: false
+        },
+        {
+          id: 'cloudflare',
+          name: 'Cloudflare DNS',
+          description: 'Managed DNS with API access — no self-hosting needed',
+          icon: '🔶',
+          difficulty: 'Easy',
+          features: [
+            'Fully managed, no server needed',
+            'API for automated record management',
+            'Global anycast network',
+            'Free tier available'
+          ],
+          recommended: false,
+          providerId: 'cloudflare'
+        },
+        {
+          id: 'external',
+          name: 'External / Manual DNS',
+          description: 'Use your own DNS provider (cPanel, Route53, etc.)',
+          icon: '🔗',
+          difficulty: 'Easy',
+          features: [
+            'Works with any DNS provider',
+            'DashCaddy shows you what records to create',
+            'Propagation checking still works',
+            'No API credentials needed'
+          ],
+          recommended: false,
+          providerId: 'manual'
         }
       ];
     }