Session Workflow Approval Implementation

Scope

Show the current Todo workflow inside the existing exit_plan_mode permission panel so a user can review the dependency graph before execution starts.

Implementation

1. Add an optional Todo snapshot to ToolApproval and render PlanExecutionView only for Plan Mode exit approvals.
2. Pass the active Todo snapshot from both the main session view and split session panes.
3. Preserve the ACP plan body as the text-only fallback when no Todo snapshot exists and leave non-Plan-Mode approvals unchanged.
4. Make workflow nodes selectable and show the selected Todo's full content, status, dependencies, and linked Agent executions below the graph.
5. Reuse the existing subagent detail panel for live progress and final output; do not add execution output to Todo snapshots or task polling.

Verification

• Component test: Plan Mode approval renders a Todo dependency workflow.
• Component test: Plan Mode approval without Todos preserves its text content.
• Adapter test: ACP exit-plan content reaches the approval request.
• Wiring tests: main and split session approvals receive their own active Todo snapshot.
• Workflow test: selecting a node exposes its details and linked subagent opens the existing detail callback.
• Run the focused Web Shell tests, typecheck, and build.