Detect subagent tool_call events (Agent/Task/dispatch_agent), auto-spawn
child agent panes with parent/child navigation. Messages with parentId
are routed to child panes; parent session keeps its own messages.
- agents.svelte.ts: parent/child hierarchy fields, findChildByToolUseId,
getChildSessions, parent-aware createAgentSession/removeAgentSession
- agent-dispatcher.ts: SUBAGENT_TOOL_NAMES detection, toolUseToChildPane
routing map, spawnSubagentPane with auto-grouping under parent title
- AgentPane.svelte: parent link bar (SUB badge), children bar (chips
with status colors), clickable navigation between parent/child
- SessionList.svelte: subagent panes show arrow icon instead of asterisk
07fc52b958