DC-033: fix getLocalVersion __dirname resolution

The SelfUpdater's getLocalVersion() used __dirname to find package.json
and VERSION, but server.js loads the module via './src/docker/self-updater'
so __dirname resolves to /app/src/docker inside the container — which
has no package.json. Result: /api/v1/system/version silently returned
{version: '0.0.0', commit: null} and checkForUpdate() always thought we
were outdated.

Walk a candidate list of paths (api root first, __dirname second) so the
function works regardless of where the module is required from. Log to
stderr on total failure instead of swallowing silently.

Verified on DNS2: /api/v1/system/version now returns
{"name":"DashCaddy","version":"1.14.8","commit":"fef7e07"}
(v1.14.8 with the security fixes DC-020..032).

dashcaddy-api/src/docker/self-updater.js

@@ -105,16 +105,27 @@ class SelfUpdater extends EventEmitter {
   // ── Version / Identity Info ──
 
   getLocalVersion() {
-    try {
-      const pkg = JSON.parse(fs.readFileSync(path.join(__dirname, 'package.json'), 'utf8'));
-      let commit = null;
+    // Resolve package.json/VERSION relative to the api root, not __dirname.
+    // This module is loaded via `./src/docker/self-updater` so __dirname is
+    // `/app/src/docker` inside the container, which has no package.json.
+    // Fall back to __dirname (matches the legacy root-copy contract) so
+    // existing callers and future restructurings keep working.
+    const candidates = [
+      path.join(__dirname, '..', '..', 'package.json'),
+      path.join(__dirname, 'package.json'),
+    ];
+    for (const pkgPath of candidates) {
       try {
-        commit = fs.readFileSync(path.join(__dirname, 'VERSION'), 'utf8').trim();
-      } catch { /* ignore */ }
-      return { version: pkg.version, commit };
-    } catch (e) {
-      return { version: '0.0.0', commit: null };
+        const pkg = JSON.parse(fs.readFileSync(pkgPath, 'utf8'));
+        let commit = null;
+        try {
+          commit = fs.readFileSync(pkgPath.replace(/package\.json$/, 'VERSION'), 'utf8').trim();
+        } catch { /* ignore */ }
+        return { version: pkg.version, commit };
+      } catch { /* try next candidate */ }
     }
+    console.error('[SelfUpdater] getLocalVersion failed: no candidate package.json found');
+    return { version: '0.0.0', commit: null };
   }
 
   getInstanceInfo() {