feat(web): live step list, option choice card and inline approval card; drop run mode switch

- session page shows the agent.plan TodoList (drawer: one-line progress); options and approval
  cards sit at their step; composer has a "先看方案再执行" toggle instead of the mode switch
- settings expose option timeout, timeout action and approval validity; quick goals follow glossary

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/web/app/components/agent/agent-subagent-tree.tsx

@@ -57,7 +57,6 @@ function Node({ node, byParent, depth }: { node: AgentRunNode; byParent: Map<str
           </Link>
           <div className="mt-0.5 flex flex-wrap items-center gap-1.5">
             <RunStatusBadge status={node.status} />
-            {node.mode === "plan_only" ? <span className="text-meta text-muted-foreground">只要方案</span> : null}
             <span className="text-meta text-muted-foreground tabular-nums">
               {usageLine({
                 toolCalls: node.toolCallCount,