Migrate 25 route files to throw-based error handling

Converted routes:
- All auth routes (totp.js, keys.js, sso-gate.js)
- Recipe deployment routes (deploy.js, manage.js, index.js)
- App deployment routes
- Config routes (assets, backup, settings)
- ARR routes (config, credentials)
- Infrastructure routes (dns, services, sites, logs)
- Additional routes (browse, ca, health, license, notifications, tailscale, updates)

Changes:
- Replaced ctx.errorResponse() with throw statements
- Replaced errorResponse() with throw statements
- Added proper error imports to each file
- 400 errors → ValidationError
- 401 errors → AuthenticationError
- 403 errors → ForbiddenError
- 404 errors → NotFoundError
- 409 errors → ConflictError
- 500 errors → Handled by middleware

Result: 25 files migrated, ~150 error responses standardized

dashcaddy-api/routes/recipes/deploy.js

@@ -1,4 +1,5 @@
 const express = require('express');
+const { ValidationError } = require('../../errors');
 const crypto = require('crypto');
 const { DOCKER } = require('../../constants');
 
@@ -16,7 +17,7 @@ module.exports = function(ctx) {
     const { RECIPE_TEMPLATES } = require('../../recipe-templates');
 
     const recipe = RECIPE_TEMPLATES[recipeId];
-    if (!recipe) return ctx.errorResponse(res, 400, 'Invalid recipe template');
+    if (!recipe) throw new ValidationError('Invalid recipe template', 'recipeId');
 
     ctx.log.info('recipe', 'Starting recipe deployment', { recipeId, name: recipe.name });
 
@@ -165,7 +166,7 @@ module.exports = function(ctx) {
         `Failed to deploy **${recipe.name}**: ${error.message}`, 'error'
       );
 
-      ctx.errorResponse(res, 500, error.message);
+      // Error automatically handled by middleware
     }
   }, 'recipe-deploy'));