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/config/assets.js

@@ -3,6 +3,7 @@ const fsp = require('fs').promises;
 const path = require('path');
 const { LIMITS } = require('../../constants');
 const { exists } = require('../../fs-helpers');
+const { ValidationError } = require('../errors');
 
 // Image processing for favicon conversion (optional)
 let sharp, pngToIco;
@@ -22,19 +23,19 @@ module.exports = function(ctx) {
     const { filename, data } = req.body;
 
     if (!filename || !data) {
-      return ctx.errorResponse(res, 400, 'filename and data are required');
+      throw new ValidationError('filename and data are required');
     }
 
     // Validate filename to prevent directory traversal
     const safeFilename = path.basename(filename);
     if (safeFilename !== filename || filename.includes('..')) {
-      return ctx.errorResponse(res, 400, 'Invalid filename - must not contain path separators');
+      throw new ValidationError('Invalid filename - must not contain path separators');
     }
 
     // Extract base64 data
     const matches = data.match(/^data:image\/([a-zA-Z+]+);base64,(.+)$/);
     if (!matches) {
-      return ctx.errorResponse(res, 400, 'Invalid image data format');
+      throw new ValidationError('Invalid image data format');
     }
 
     const extension = matches[1] === 'svg+xml' ? 'svg' : matches[1];
@@ -103,7 +104,7 @@ module.exports = function(ctx) {
     const { data, dataDark, dataLight, position, dashboardTitle } = req.body;
 
     if (!data && !dataDark && !dataLight && !position && !dashboardTitle) {
-      return ctx.errorResponse(res, 400, 'Image data, position, or title is required');
+      throw new ValidationError('Image data, position, or title is required');
     }
 
     const config = await ctx.readConfig();
@@ -112,19 +113,19 @@ module.exports = function(ctx) {
     // New dual-variant upload
     if (dataDark) {
       pathDark = await saveLogoFile(dataDark, 'dark');
-      if (!pathDark) return ctx.errorResponse(res, 400, 'Invalid dark logo data format');
+      if (!pathDark) throw new ValidationError('Invalid dark logo data format');
       config.customLogoDark = pathDark;
     }
     if (dataLight) {
       pathLight = await saveLogoFile(dataLight, 'light');
-      if (!pathLight) return ctx.errorResponse(res, 400, 'Invalid light logo data format');
+      if (!pathLight) throw new ValidationError('Invalid light logo data format');
       config.customLogoLight = pathLight;
     }
 
     // Legacy single-logo: save as both variants
     if (data && !dataDark && !dataLight) {
       const singlePath = await saveLogoFile(data, 'dark');
-      if (!singlePath) return ctx.errorResponse(res, 400, 'Invalid image data format');
+      if (!singlePath) throw new ValidationError('Invalid image data format');
       config.customLogoDark = singlePath;
       config.customLogoLight = singlePath;
       // Also set legacy field for backward compat
@@ -208,7 +209,7 @@ module.exports = function(ctx) {
     const { data } = req.body;
 
     if (!data) {
-      return ctx.errorResponse(res, 400, 'Image data is required');
+      throw new ValidationError('Image data is required');
     }
 
     if (!sharp || !pngToIco) {
@@ -218,7 +219,7 @@ module.exports = function(ctx) {
     // Extract base64 data
     const matches = data.match(/^data:image\/([a-zA-Z+]+);base64,(.+)$/);
     if (!matches) {
-      return ctx.errorResponse(res, 400, 'Invalid image data format');
+      throw new ValidationError('Invalid image data format');
     }
 
     const imageType = matches[1];