wip: context-meter + model-label UI and provider/inference tweaks

Checkpoint of in-flight work so the orchestrator branch can rebase onto a
clean main: ContextBar → ContextMeter, model-label helper, model/agent picker
+ provider-snapshot/registry changes, inference payload + message-columns.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/web/src/components/panes/CoderPane.tsx

@@ -4,7 +4,8 @@
 // WS: /api/coder/ws/sessions/:id (Vite dev proxies to :9502).
 
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
-import { Code, Check, X, RefreshCw, Terminal, Puzzle, Sparkles } from 'lucide-react';
+import { Check, X, RefreshCw, Terminal, Puzzle, Sparkles } from 'lucide-react';
+import mascot from '@/assets/brand/banner-mascot.png';
 import { AgentComposerBar } from '@/components/AgentComposerBar';
 import { PermissionCard } from '@/components/PermissionCard';
 import { ChatInput } from '@/components/ChatInput';
@@ -1085,8 +1086,8 @@ export function CoderPane({
       {/* Chat area — BooChat-style timeline (text + tool runs as siblings) */}
       <div className="flex-1 min-h-0 flex flex-col">
         {messages.length === 0 ? (
-          <div className="flex flex-col items-center justify-center flex-1 text-sm text-muted-foreground gap-2">
-            <Code size={32} className="opacity-40" />
+          <div className="flex flex-col items-center justify-center flex-1 text-sm text-muted-foreground gap-3">
+            <img src={mascot} alt="BooCode" draggable={false} className="w-20 h-auto select-none" />
             <p>{chatPending || !chatId ? 'Preparing pane chat…' : 'Send a message to start coding'}</p>
           </div>
         ) : (