Add electron-builder packaging configuration

- Install electron-builder as dev dependency
- Configure build targets for macOS (dmg, zip), Windows (nsis, zip), and Linux (AppImage, deb)
- Add npm scripts for building unpacked app (dist:dir) and macOS packages (dist:mac)
- Set base path to "./" in production builds for proper asset loading in packaged app
- Fix index.html asset paths to use relative paths (./ prefix)
- Update README to document packaging commands and note unsigned/unnotarized status

README.md

@@ -58,6 +58,8 @@ npm run dev:renderer   # Vite frontend only
 npm run dev:electron   # Electron only, expects renderer on port 1420
 npm run build          # TypeScript + Vite production build
 npm run desktop        # Run Electron against the built dist/
+npm run dist:dir       # Build an unpacked Electron app in release/
+npm run dist:mac       # Build macOS .dmg and .zip packages in release/
 ```
 
 ## Production-Like Local Run
@@ -119,16 +121,18 @@ Current limitation:
 
 That is convenient for development, but it is not the right long-term storage mechanism for a production desktop app. A future improvement should move credentials into the OS keychain or another secure secret store.
 
-## Packaging Status
+## Packaging
 
-Electron packaging for release builds is not set up yet.
+Electron packaging is set up with `electron-builder`.
 
-Right now, the repository supports:
+Current packaging commands:
 
-- local development with `npm run dev:desktop`
-- local production-style execution with `npm run build && npm run desktop`
+- `npm run dist:dir` creates an unpacked app bundle in `release/`
+- `npm run dist:mac` creates macOS `.dmg` and `.zip` artifacts in `release/`
 
-If you want distributable `.dmg`, `.AppImage`, `.deb`, or `.exe` artifacts, the next step is to add an Electron packaging tool such as Electron Forge or electron-builder.
+The current mac build is unsigned and not notarized, which is fine for local use and testing but not enough for friction-free public distribution through Gatekeeper.
+
+Windows and Linux targets are also configured in `package.json`, but they have not been validated in this repository yet.
 
 ## Legacy Tauri Script