Add response metrics: elapsed time, tool calls, token count ...

Server:
- Message model: elapsed_seconds, tool_call_count, token_count fields
  (display-only, excluded from LLM context via exclude_none)
- StreamEnd event: carries same three fields
- agent.run_stream: tracks turn start time, counts ToolEvent completions,
  writes metrics onto the final assistant Message before saving to DB
- WebSocket: forwards metrics in stream_end payload

Client:
- chat.onStreamEnd: attaches elapsed_seconds, tool_call_count, token_count
  to the streaming message on completion
- buildMessageList: scans each assistant group for metrics from history
- AssistantMessage: renders .msg-meta-row below the response —
  timer icon + Xs · wrench icon + N tools · coins icon + Nk tokens · time
  (each item only shown if present; time pushed right via margin-left: auto)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

webclient: UI density improvements for session names and header ...

Sidebar:
- session-name: 12px → 13px (more prominent with real names)
- session-preview: 13px → 12px, clamp 2 → 3 lines (more content visible)
- session-actions buttons: 26×26px, gap 2px (narrower, more room for info)

Chat header (mobile):
- chat-header-info: column layout on mobile so title and profile badge
  stack vertically (flex-direction: column; align-items: flex-start)

ContextBar:
- Recomposed to single row: [track] [pct%]
- Track 100px → 60px, height 5px → 4px
- Full token counts moved to title attribute (hover tooltip)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

webclient: remove 'Planning' label from wait indicator; add scroll-to-bottom button ...

- Waiting indicator now shows only a spinner (text was misleading — model
  doesn't always plan before responding)
- Add floating scroll-to-bottom button that appears when scrolled >200px
  from bottom, disappears when near bottom; smooth fade+slide transition;
  positioned bottom-right (under thumb on mobile)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

webclient: fix history scroll by hiding content until positioned ...

Hide message-list-inner (opacity: 0) before scrolling to bottom,
then reveal it — so the user never sees the jump from top to bottom
on page reload or session switch. Content fades in already at the
correct scroll position.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

webclient: message timestamps, confirm dialog, layout and UX fixes ...

- Add useTime.js: relative time labels ("just now", "5m ago", HH:MM) with auto-refresh every 30s
- Show message timestamps below user bubbles and assistant replies
- Show session last_active time in sidebar below preview
- Add ConfirmDialog.vue + useConfirm.js: kit-styled modal confirm, wired to delete in SessionItem
- SessionList: switch RecycleScroller → DynamicScroller to support variable item heights
- SessionItem: remove fixed 74px height; show action buttons always on touch devices (hover: none)
- MessageList: constrain content to max-width 920px centered (message-list-inner, input-row)
- MessageList: replace TransitionGroup with plain v-for; animate only new messages via .msg-enter CSS class, history loads silently without scroll animation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Fix scroll-to-bottom after page reload ...

Watch chat.loading instead of currentId for post-load scroll.
nextTick + rAF ensures browser layout is settled before scrolling.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ThinkingCard: add chevron, open by default; plan loading indicator ...

- ThinkingCard: add ph-caret-down chevron (matches plan/tool card style),
  open by default (removed auto-close on thinking_end)
- AssistantMessage: show "Planning…" spinner when streaming but no content
  yet — gives feedback during the two-LLM-call planning phase
- app.scss: thinking-chevron styles, planning-indicator styles

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Migrate to Vue webclient; rename old client to old_webclient ...

- client/ → old_webclient/ (vanilla JS client preserved as reference)
- webclient/ — new Vue 3 + Pinia webclient (source + dist build)
- vite.config.js: outDir changed to webclient/dist/
- main.py: serve /assets and /images from webclient/dist/,
  index.html from webclient/dist/index.html
- .gitignore: exclude webclient/node_modules/, include webclient/dist/

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>