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/

go.mod

@@ -5,9 +5,7 @@ go 1.25.0
 require github.com/wailsapp/wails/v2 v2.11.0
 
 require (
-	filippo.io/edwards25519 v1.2.0 // indirect
 	github.com/bep/debounce v1.2.1 // indirect
-	github.com/danieljoos/wincred v1.2.3 // indirect
 	github.com/go-ole/go-ole v1.3.0 // indirect
 	github.com/godbus/dbus/v5 v5.2.2 // indirect
 	github.com/google/uuid v1.6.0 // indirect
@@ -24,24 +22,15 @@ require (
 	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
-	github.com/rs/zerolog v1.35.1 // indirect
 	github.com/samber/lo v1.49.1 // indirect
 	github.com/stretchr/testify v1.11.1 // indirect
-	github.com/tidwall/gjson v1.19.0 // indirect
-	github.com/tidwall/match v1.1.1 // indirect
-	github.com/tidwall/pretty v1.2.1 // indirect
-	github.com/tidwall/sjson v1.2.5 // indirect
 	github.com/tkrajina/go-reflector v0.5.8 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	github.com/valyala/fasttemplate v1.2.2 // indirect
 	github.com/wailsapp/go-webview2 v1.0.22 // indirect
 	github.com/wailsapp/mimetype v1.4.1 // indirect
-	github.com/zalando/go-keyring v0.2.8 // indirect
-	go.mau.fi/util v0.9.9 // indirect
 	golang.org/x/crypto v0.51.0 // indirect
-	golang.org/x/exp v0.0.0-20260508232706-74f9aab9d74a // indirect
 	golang.org/x/net v0.54.0 // indirect
 	golang.org/x/sys v0.44.0 // indirect
 	golang.org/x/text v0.37.0 // indirect
-	maunium.net/go/mautrix v0.28.0 // indirect
 )