0.34.1: populate the log container filter (parse compose prefix)

The whole-stack log stream sends service:null on every line, so the
container filter dropdown only ever showed "All containers". docker compose
logs already prefixes each line with the container name (and an RFC3339
timestamp via --timestamps); parse that prefix client-side to recover the
container, populate the filter, and render time + container + message
separately (cleaner than the raw prefixed line).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/package.json

@@ -1,7 +1,7 @@
 {
   "name": "stackpilot-frontend",
   "private": true,
-  "version": "0.34.0",
+  "version": "0.34.1",
   "type": "module",
   "scripts": {
     "dev": "vite",