chore: remove usage tracking and logging functionality

- Deleted the `LoggerPlugin` along with associated usage tracking and in-memory statistics logic.
- Removed all related tests (`logger_plugin_test.go`, `usage_tab_test.go`) and external-facing handler (`usage.go`) for usage statistics export/import.
- Cleaned up TUI integration by deleting `usage_tab.go`.

internal/tui/app.go

@@ -18,7 +18,6 @@ const (
 	tabAuthFiles
 	tabAPIKeys
 	tabOAuth
-	tabUsage
 	tabLogs
 )
 
@@ -40,7 +39,6 @@ type App struct {
 	auth      authTabModel
 	keys      keysTabModel
 	oauth     oauthTabModel
-	usage     usageTabModel
 	logs      logsTabModel
 
 	client *Client
@@ -50,7 +48,7 @@ type App struct {
 	ready  bool
 
 	// Track which tabs have been initialized (fetched data)
-	initialized [7]bool
+	initialized [6]bool
 }
 
 type authConnectMsg struct {
@@ -81,10 +79,9 @@ func NewApp(port int, secretKey string, hook *LogHook) App {
 		auth:          newAuthTabModel(client),
 		keys:          newKeysTabModel(client),
 		oauth:         newOAuthTabModel(client),
-		usage:         newUsageTabModel(client),
 		logs:          newLogsTabModel(client, hook),
 		client:        client,
-		initialized: [7]bool{
+		initialized: [6]bool{
 			tabDashboard: true,
 			tabLogs:      true,
 		},
@@ -92,7 +89,7 @@ func NewApp(port int, secretKey string, hook *LogHook) App {
 
 	app.refreshTabs()
 	if authRequired {
-		app.initialized = [7]bool{}
+		app.initialized = [6]bool{}
 	}
 	app.setAuthInputPrompt()
 	return app
@@ -128,7 +125,6 @@ func (a App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		a.auth.SetSize(contentW, contentH)
 		a.keys.SetSize(contentW, contentH)
 		a.oauth.SetSize(contentW, contentH)
-		a.usage.SetSize(contentW, contentH)
 		a.logs.SetSize(contentW, contentH)
 		return a, nil
 
@@ -142,7 +138,7 @@ func (a App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		a.authenticated = true
 		a.logsEnabled = a.standalone || isLogsEnabledFromConfig(msg.cfg)
 		a.refreshTabs()
-		a.initialized = [7]bool{}
+		a.initialized = [6]bool{}
 		a.initialized[tabDashboard] = true
 		cmds := []tea.Cmd{a.dashboard.Init()}
 		if a.logsEnabled {
@@ -258,8 +254,6 @@ func (a App) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		a.keys, cmd = a.keys.Update(msg)
 	case tabOAuth:
 		a.oauth, cmd = a.oauth.Update(msg)
-	case tabUsage:
-		a.usage, cmd = a.usage.Update(msg)
 	case tabLogs:
 		a.logs, cmd = a.logs.Update(msg)
 	}
@@ -322,8 +316,6 @@ func (a *App) initTabIfNeeded(_ int) tea.Cmd {
 		return a.keys.Init()
 	case tabOAuth:
 		return a.oauth.Init()
-	case tabUsage:
-		return a.usage.Init()
 	case tabLogs:
 		if !a.logsEnabled {
 			return nil
@@ -360,8 +352,6 @@ func (a App) View() string {
 		sb.WriteString(a.keys.View())
 	case tabOAuth:
 		sb.WriteString(a.oauth.View())
-	case tabUsage:
-		sb.WriteString(a.usage.View())
 	case tabLogs:
 		if a.logsEnabled {
 			sb.WriteString(a.logs.View())
@@ -529,10 +519,6 @@ func (a App) broadcastToAllTabs(msg tea.Msg) (tea.Model, tea.Cmd) {
 	if cmd != nil {
 		cmds = append(cmds, cmd)
 	}
-	a.usage, cmd = a.usage.Update(msg)
-	if cmd != nil {
-		cmds = append(cmds, cmd)
-	}
 	a.logs, cmd = a.logs.Update(msg)
 	if cmd != nil {
 		cmds = append(cmds, cmd)