infra/docs: Docker Hub release pipeline, versioning, README overhaul

Reference prebuilt temetro/temetro-{backend,frontend} images in docker-compose
(with a build fallback) and stop baking the frontend API URL. Add a
tag-triggered GitHub Actions release workflow that pushes both images and cuts
a GitHub Release, plus RELEASING.md, CHANGELOG.md, and a root version. Overhaul
the root and frontend READMEs (screenshot, features, prebuilt-image quickstart,
LAN access, updating).

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

package.json

@@ -1,5 +1,11 @@
 {
+  "name": "temetro",
+  "version": "0.1.0",
+  "private": true,
   "devDependencies": {
     "shadcn": "^4.11.0"
+  },
+  "dependencies": {
+    "xcodebuildmcp": "^2.6.2"
   }
 }