fix: normalize timestamps in SessionsPanel and server lastActive (#278 cherry-pick)

Cherry-pick the SessionsPanel.tsx and server.py fixes from PR #278
that were not covered by the merged #282:
- SessionsPanel: use shared formatDashboardTime for activity timestamps
- server.py: convert lastActive to local timezone in get_task_activity()

dashboard/server.py

@@ -1978,13 +1978,24 @@ def get_task_activity(task_id):
         except Exception:
             pass
 
+    last_active = None
+    if updated_at:
+        try:
+            dt = _parse_iso(updated_at)
+            if dt:
+                last_active = dt.astimezone().strftime('%Y-%m-%d %H:%M:%S')
+            else:
+                last_active = updated_at[:19].replace('T', ' ')
+        except Exception:
+            last_active = updated_at[:19].replace('T', ' ')
+
     result = {
         'ok': True,
         'taskId': task_id,
         'taskMeta': task_meta,
         'agentId': agent_id,
         'agentLabel': _STATE_LABELS.get(state, state),
-        'lastActive': updated_at[:19].replace('T', ' ') if updated_at else None,
+        'lastActive': last_active,
         'activity': activity,
         'activitySource': 'progress+session',
         'relatedAgents': sorted(list(related_agents)),

edict/frontend/src/components/SessionsPanel.tsx

@@ -1,6 +1,7 @@
 import { useStore, isEdict, STATE_LABEL, timeAgo } from '../store';
 import type { Task } from '../api';
 import { useState } from 'react';
+import { formatDashboardTime } from '../time';
 
 // Agent maps built from agentConfig
 function useAgentMaps() {
@@ -231,7 +232,7 @@ function SessionDetailModal({
                 const kLabel = kind === 'assistant' ? '回复' : kind === 'tool' ? '工具' : kind === 'user' ? '用户' : '事件';
                 let txt = (a.text || '').replace(/\[\[.*?\]\]/g, '').replace(/\*\*/g, '').trim();
                 if (txt.length > 200) txt = txt.substring(0, 200) + '…';
-                const time = ((a.at as string) || '').substring(11, 19);
+                const time = formatDashboardTime(a.at as string | number | undefined, { showSeconds: true });
                 return (
                   <div key={i} style={{ padding: '8px 12px', borderBottom: '1px solid var(--line)', fontSize: 12, lineHeight: 1.5 }}>
                     <div style={{ display: 'flex', alignItems: 'center', gap: 6, marginBottom: 3 }}>