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)

dashcaddy-api/routes/apps/removal.js

@@ -71,18 +71,13 @@ module.exports = function({
       if (shouldDeleteContainer && subdomain && ctx.dns.getToken()) {
         try {
           const domain = ctx.buildDomain(subdomain);
-          const getResult = await ctx.dns.call(ctx.siteConfig.dnsServerIp, '/api/zones/records/get', {
-            token: ctx.dns.getToken(), domain, zone: ctx.siteConfig.tld.replace(/^\./, ''), listZone: 'true'
-          });
+          const resolveResult = await ctx.dns.universalResolveRecord(domain, 'A');
           let recordIp = ip || 'localhost';
-          if (getResult.status === 'ok' && getResult.response?.records) {
-            const aRecord = getResult.response.records.find(r => r.type === 'A');
-            if (aRecord && aRecord.rData?.ipAddress) recordIp = aRecord.rData.ipAddress;
+          if (resolveResult) {
+            recordIp = resolveResult;
           }
-          const dnsResult = await ctx.dns.call(ctx.siteConfig.dnsServerIp, '/api/zones/records/delete', {
-            token: ctx.dns.getToken(), domain, type: 'A', ipAddress: recordIp
-          });
-          results.dns = dnsResult.status === 'ok' ? 'deleted' : (dnsResult.errorMessage || 'failed');
+          await ctx.dns.universalDeleteRecord(domain, recordIp);
+          results.dns = 'deleted';
           log.info('dns', 'DNS record removal', { result: results.dns });
         } catch (error) {
           results.dns = error.message;