fix: resolve TDZ error when switching back to chat page

Move sourceLabel and getSourceLabel before groupedSessions computed
to fix "Cannot access before initialization" in production build.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "hermes-web-ui",
-  "version": "0.1.5",
+  "version": "0.1.6",
   "description": "Hermes Agent Web UI - Chat and Job Management Dashboard",
   "repository": {
     "type": "git",