DC-039: route all module file defaults through platformPaths.dataDir

Multiple modules derived file paths from __dirname, which is unstable in two
ways: (1) it moves whenever the file is reorganized under src/, and (2) it
points to the in-container source dir /app/src/<x> in production, which is
not bind-mounted, so writes would silently land in the image layer.

Affected modules (10 files): backup-manager, resource-monitor, update-manager,
docker-security, audit-logger, bundled-workflows, port-lock-manager, logging,
error-handler, license-keygen, plus crypto-utils and credential-manager which
already had multi-candidate resolvers but no centralised fallback.

Introduced platformPaths.dataDir (derived from SERVICES_FILE/CONFIG_FILE/
DNS_CREDENTIALS_FILE env vars when set, else path.dirname(servicesFile)) so
every module resolves the same canonical data directory. Each module now
fans the runtime files into the data dir while preserving per-file env-var
overrides for custom deployments.

Why a single resolver:
  - one place to swap the default path scheme in v2.x without chasing
    hardcoded __dirname joins
  - a single source-of-truth for tests, backup tools, and the soon-to-be
    added single-volume migration script
  - prevents the class of DC-033 (self-updater 0.0.0) bugs where __dirname
    drift in a subdirectory silently loses runtime state

Also fixed:
  - audit-logger: AUDIT_LOG_FILE default was /app/src/security/audit-log.json
    (writable in dev, image-layer in production). Now /app/data/audit-log.json
    via platformPaths.dataDir, matching logging.js's same file. Same physical
    path, no behavior change for callers that already set AUDIT_LOG_FILE.
  - logging.js: LOG_DIR was __dirname (src/utils/) — error.log and
    audit-log.json were being written into the source tree. Now
    platformPaths.dataDir, matching every other persistent file.
  - error-handler.js: ERROR_LOG_FILE hard-coded to __dirname/error.log
    (src/utilities/error.log), redundant with logging.js's own default.
    Now platformPaths.dataDir/error.log.
  - host-registry / event-store / event-workers: simplified the
    'platformPaths.dataDir || path.join(__dirname, ../../data)' pattern
    to just platformPaths.dataDir (the legacy fallback is no longer
    reachable — services.json lives at dataDir/services.json now).
  - public-routes-drift.test.js: added 'routes/security.js' to the
    direct-mount list so the /api/v1/security/events/ingest and
    /api/v1/security/events/batch entries in PUBLIC_ROUTES are
    recognized as mounted (was missing — fixed DC-044's drift-detection
    test gap).

Tests: 1214/1214 pass (0 new failures, 1 new test for the corrected route
mount detection path). ESLint: 146 warnings + 4 errors — same baseline as
HEAD (no new warnings or errors introduced; one pre-existing require-await
on readline was removed as a drive-by in event-workers.js since the module
uses line-level fs reads, not readline). Container config files like
audit-log.json, container-stats.json, and workflow-history.json still
exist on the running container's image layer — Docker will pick up the
new defaults on the next recreate (the update path already moves
services.json+config.json+credentials.json via the data bind mount).

dashcaddy-api/src/security/crypto-utils.js

@@ -7,6 +7,7 @@
 const crypto = require('crypto');
 const fs = require('fs');
 const path = require('path');
+const platformPaths = require('../../platform-paths');
 
 // Encryption settings
 const ALGORITHM = 'aes-256-gcm';
@@ -15,23 +16,14 @@ const IV_LENGTH = 16;  // 128 bits for GCM
 const AUTH_TAG_LENGTH = 16;
 const SALT_LENGTH = 32;
 
-// Resolve encryption key file path — supports both standard install (/app/.encryption-key)
-// and custom deployments with consolidated data directory (/app/data/.encryption-key)
+// Resolve the encryption key alongside the canonical services/config state.
+// platformPaths.dataDir supports both current /app/data mounts and legacy /app
+// single-file mounts, and does not change when this module moves within src/.
 function resolveKeyFile() {
   if (process.env.ENCRYPTION_KEY_FILE) {
     return process.env.ENCRYPTION_KEY_FILE;
   }
-  const candidates = [
-    path.join(__dirname, '.encryption-key'),
-    path.join(__dirname, 'data', '.encryption-key'),
-  ];
-  for (const candidate of candidates) {
-    if (fs.existsSync(candidate)) {
-      return candidate;
-    }
-  }
-  // No existing file — return standard path so first load creates it there
-  return candidates[0];
+  return path.join(platformPaths.dataDir, '.encryption-key');
 }
 
 const KEY_FILE = resolveKeyFile();
@@ -149,7 +141,7 @@ function loadOrCreateKey() {
  */
 function tryFallbackToBackupKey(primaryKey, backupKey) {
   const CREDENTIALS_FILE = process.env.CREDENTIALS_FILE ||
-    require('path').join(__dirname, 'credentials.json');
+    path.join(platformPaths.dataDir, 'credentials.json');
   if (!fs.existsSync(CREDENTIALS_FILE)) return primaryKey;
 
   let credentials;