fix(plugin): normalize event session ids

Handle OpenCode session events that carry the session ID under properties.info.id or properties.info.sessionID so background tasks and continuation hooks do not miss idle/error/delete events.

Add regression coverage for nested session.idle events completing background tasks and waking continuation hooks.

src/hooks/team-session-events/team-member-error-handler.ts

@@ -1,14 +1,14 @@
 import type { TeamModeConfig } from "../../config/schema/team-mode"
 import { findResolvedMemberSession } from "../../features/team-mode/member-session-resolution"
 import { loadRuntimeState, transitionRuntimeState } from "../../features/team-mode/team-state-store/store"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 
 type HookInput = { event: { type: string; properties?: unknown } }
 export type HookImpl = (input: HookInput) => Promise<void>
 
 function getErroredSessionID(properties: unknown): string | undefined {
-  const record = properties as { sessionID?: string } | undefined
-  return record?.sessionID
+  return resolveSessionEventID(properties)
 }
 
 export function createTeamMemberErrorHandler(config: TeamModeConfig): HookImpl {