chore: sync all package versions to 0.1.2, document versioning rule

Author: prakersh

CLAUDE.md

@@ -35,6 +35,13 @@ pnpm build                     # Production build (tsc + vite)
 FDP_AUTH__MODE=multi uv run uvicorn fourdpocket.main:app --port 4040
 ```
 
+## Versioning
+
+All three version files must stay in sync when bumping:
+- `pyproject.toml` (backend)
+- `frontend/package.json` (frontend)
+- `extension/package.json` (Chrome extension)
+
 ## Project Structure
 
 ```

extension/package.json

@@ -1,6 +1,6 @@
 {
   "name": "4dpocket-extension",
-  "version": "1.0.0",
+  "version": "0.1.2",
   "private": true,
   "type": "module",
   "scripts": {

frontend/package.json

@@ -1,7 +1,7 @@
 {
   "name": "frontend",
   "private": true,
-  "version": "0.0.0",
+  "version": "0.1.2",
   "type": "module",
   "license": "GPL-3.0-only",
   "scripts": {