feat: login MAS OIDC end-to-end (issue 0147)

Backend Go:
- MatrixService with Login/GetSession/Logout bindings
- Uses 3 registry helpers via go.work:
  - mas_oidc_loopback_go_infra (PKCE flow)
  - keyring_token_store_go_infra (SO keychain)
  - matrix_client_init_go_infra (mautrix client)
- whoami helper to discover user_id+device_id pre-init

Frontend React+Vite+TS:
- Mantine v7 + @tabler/icons-react
- LoginScreen with 'Sign in with Matrix' button
- HomeScreen with profile card + logout
- Dark theme violet accent
- @mantine/notifications wired

Wails config:
- Switched to pnpm (workspace: protocol)
- Bindings auto-generated for MatrixService
- 1280x800 default window

Build: 68MB linux/amd64 binary in build/bin/

main.go

@@ -1,7 +1,9 @@
 package main
 
 import (
+	"context"
 	"embed"
+	"log"
 
 	"github.com/wailsapp/wails/v2"
 	"github.com/wailsapp/wails/v2/pkg/options"
@@ -12,25 +14,24 @@ import (
 var assets embed.FS
 
 func main() {
-	// Create an instance of the app structure
-	app := NewApp()
+	ms := NewMatrixService()
 
-	// Create application with options
 	err := wails.Run(&options.App{
 		Title:  "matrix_client_pc",
-		Width:  1024,
-		Height: 768,
+		Width:  1280,
+		Height: 800,
 		AssetServer: &assetserver.Options{
 			Assets: assets,
 		},
-		BackgroundColour: &options.RGBA{R: 27, G: 38, B: 54, A: 1},
-		OnStartup:        app.startup,
+		BackgroundColour: &options.RGBA{R: 26, G: 27, B: 30, A: 1},
+		OnStartup: func(ctx context.Context) {
+			ms.SetContext(ctx)
+		},
 		Bind: []interface{}{
-			app,
+			ms,
 		},
 	})
-
 	if err != nil {
-		println("Error:", err.Error())
+		log.Fatalln("Wails error:", err)
 	}
 }