Merge krystie-improvements into main

Resolves 24 conflicts between Hermes (DC-008/009/010 + response-helper
envelope standardization) and Krystie (DC-005 src/ refactor path fixes,
DC-006 TOTP integration, DC-007 new test suites, cloud backup
destinations).

Conflict resolutions:
- src/utils/logging.js:    took ours (consumers depend on logError/
                            safeErrorMessage/createLogger exports)
- src/config/site.js:      merged (her factored validateAndLogConfig +
                            applyConfigFields helpers)
- src/context/dns.js:      took hers (admin/readonly role iteration for
                            write operations)
- src/utilities/backup-
  manager.js:              took hers (Dropbox/WebDAV/SFTP cloud feature)
- status/dist/*, status/
  sw.js:                   took hers (minified bundles + newer SW cache)

Additional fix (post-merge regression):
- src/monitoring/health-checker.js: fixed DC-005 path miss —
  'require(./platform-paths)' → 'require(../../platform-paths)'

Test status: 921/922 passing. One known failure in logging.test.js
(async file-handle timing) tracked as follow-up.

dashcaddy-installer/src/main/config-manager.js

@@ -6,7 +6,7 @@ const { REQUIRED_DIRS } = require('../shared/constants');
 let cryptoUtils;
 try {
   // Try to load from dashcaddy-api if available
-  cryptoUtils = require('../../dashcaddy-api/crypto-utils');
+  cryptoUtils = require('../../../src/security/crypto-utils');
 } catch {
   // Fallback: create minimal crypto implementation
   const crypto = require('crypto');