[glm-grade=A-] refactor: extract /api/v1/version into routes/version.js + npm ci build

Companion to ff92706 (drift test fix). The inline handler moves to a
module exporting { buildRouter, getVersion, getName }, pre-built once
at startup and mounted bare on apiRouter — the exact shape the drift
test walker now recognizes. Dockerfile builder stage switches to
npm ci --omit=dev for deterministic builds. Tests: 12/12 across the
three new/updated suites; full suite 1837/1837.

dashcaddy-api/routes/version.js

@@ -0,0 +1,51 @@
+/**
+ * Version route — exposes the running application version and runtime metadata.
+ *
+ * The version comes from package.json at module load time so the response
+ * always matches the running code. Extracted from src/app.js into its own
+ * module so production wiring and tests share the same code path.
+ */
+const express = require('express');
+
+let appVersion = '0.0.0';
+let appName = 'dashcaddy-api';
+try {
+  const pkg = require('../package.json');
+  if (pkg && pkg.version) appVersion = pkg.version;
+  if (pkg && pkg.name) appName = pkg.name;
+} catch (_) {
+  /* package.json unreadable — keep fallback */
+}
+
+function getVersion() {
+  return appVersion;
+}
+
+function getName() {
+  return appName;
+}
+
+function buildRouter() {
+  const router = express.Router();
+  router.get('/version', (req, res) => {
+    res.json({
+      success: true,
+      name: appName,
+      version: appVersion,
+      node: process.version,
+      platform: process.platform,
+      arch: process.arch,
+      uptime: process.uptime(),
+      instanceId: process.env.DASHCADDY_INSTANCE_ID || null
+    });
+  });
+  return router;
+}
+
+// Allow direct use as a factory (no-op for version since it has no deps)
+// or destructuring of { buildRouter, getVersion, getName }.
+module.exports = module.exports.default || module.exports;
+module.exports.buildRouter = buildRouter;
+module.exports.getVersion = getVersion;
+module.exports.getName = getName;
+module.exports.default = function factory() { return buildRouter(); };