merge: foldable Vue terminal + inline prompt UX

Replaces xterm.js scrollback with a Vue-native terminal. Tool calls fold
to one-line summaries by default, Ctrl+O toggles all blocks at once,
inline prompt flows as the next scrollback line for real-terminal feel.

Author: snomiao

src/agent/composables/useAgentSession.ts

@@ -187,7 +187,16 @@ export function useAgentSession() {
           if (ac.signal.aborted) return
           toolCalls.push(inv)
           const summary = `$ ${inv.script}\n${inv.stdout}${inv.stderr ? `\n[stderr] ${inv.stderr}` : ''}`
-          store.addMessage({ role: 'system', text: summary })
+          store.addMessage({
+            role: 'system',
+            text: summary,
+            tool: {
+              script: inv.script,
+              stdout: inv.stdout,
+              stderr: inv.stderr,
+              exitCode: inv.exitCode
+            }
+          })
         }
       )
       // Fallback: model ran tools but didn't speak — surface a minimal

src/agent/shell/useCompletion.ts

@@ -16,12 +16,25 @@ export interface IngestedAsset {
   previewUrl?: string
 }
 
+interface ToolMessageMeta {
+  script: string
+  stdout: string
+  stderr?: string
+  exitCode: number
+}
+
 interface AgentMessage {
   id: string
   role: AgentMessageRole
   text: string
   assets?: IngestedAsset[]
   createdAt: number
+  /**
+   * Present on system messages that record a tool invocation. Lets the
+   * renderer fold/unfold individual tool calls by structure instead of
+   * re-parsing the synthesized text summary.
+   */
+  tool?: ToolMessageMeta
 }
 
 interface FabPosition {

src/agent/stores/agentStore.ts

@@ -1,7 +1,7 @@
 <template>
   <Teleport to="body">
     <AgentFab />
-    <XtermPanel />
+    <FoldablePanel />
   </Teleport>
 </template>
 
@@ -14,7 +14,7 @@ import { useCommandStore } from '@/stores/commandStore'
 
 import { useAgentStore } from '../stores/agentStore'
 import AgentFab from './AgentFab.vue'
-import XtermPanel from './XtermPanel.vue'
+import FoldablePanel from './FoldablePanel.vue'
 
 onMounted(() => {
   const commandStore = useCommandStore()