feat: add hook event history with badge counts in SessionLifecycleStatus

Server persists hookHistory[] per agent (cap 500, resets on SessionStart),
synced realtime via session-state-patch. Frontend computes event counts
by macro type and renders color-coded badges at the ribbon start.
Mock mode also accumulates badges during demo sequence.

frontend/src/stores/session-state.ts

@@ -31,6 +31,12 @@ export interface PendingApproval {
   timestamp: number
 }
 
+export interface HookHistoryEntry {
+  event: string
+  timestamp: number
+  detail?: string
+}
+
 export interface SessionNotification {
   id: string
   event: string
@@ -71,6 +77,7 @@ export interface AgentSessionState {
   pendingApprovals: PendingApproval[]
   terminal: AgentTerminalInfo
   notifications: SessionNotification[]
+  hookHistory: HookHistoryEntry[]
   lastHookEvent: string | null
   lastHookDetail: string | null
 }