Desktop: inspect approvals and Dynamic Workflow checkpoints

[qwen-code-dev-bot]

Parent

Parent: #105

What to build

Add an inspector that makes pending approvals and Dynamic Workflow checkpoints visible alongside the live session. Reuse the product workflow authority; approve and reject actions must identify the exact pending request and never rely on optimistic renderer-only mutation.

Acceptance criteria

• The inspector shows explicit idle, streaming, running-tool, awaiting-approval, failed, and completed states.
• A pending approval displays its exact target and supports explicit approve or reject actions.
• Dynamic Workflow checkpoint state is visible and updates from real session events.
• Tests reject stale or mismatched approval IDs and validate a safe checkpoint transition.
• A PR-bound tmux E2E receipt and screenshot prove one approval and one checkpoint transition.

Blocked by

• Desktop: render the live agent workbench #108
• Suggest Dynamic Workflow for high-complexity goals #83
• Complete a repository task end to end with Dynamic Workflow #84