web(coder UI): ChatInput migration + Thinking render + DiffPanel route fix

Bundles in-progress working-tree UI work not authored this session (CoderPane ChatInput migration, AgentComposerBar/CoderMessageList/tab-bar/sidebar/pane refinements, provider icons) with this session's changes to the same files: MessageBubble renders a collapsible 'Thinking' block from reasoning_text/reasoning_parts (surfacing ACP agent_thought_chunk + native reasoning), and the DiffPanel approve/reject calls are repointed to the real /api/coder/pending/:id/apply and /reject routes (the old /sessions/:id/pending/:id/approve|reject paths did not exist).

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

apps/web/src/components/AgentCommandsHint.tsx

@@ -9,6 +9,7 @@ interface Props {
 
 export function AgentCommandsHint({ commands }: Props) {
   const [open, setOpen] = useState(false);
+  const [expanded, setExpanded] = useState<string | null>(null);
 
   if (commands.length === 0) return null;
 
@@ -25,10 +26,19 @@ export function AgentCommandsHint({ commands }: Props) {
       {open && (
         <ul className="px-2 pb-2 space-y-1 border-t border-border/40 max-h-48 overflow-y-auto overscroll-contain touch-pan-y">
           {commands.map((cmd) => (
-            <li key={cmd.name} className="font-mono">
-              <span className="text-primary/80">/{cmd.name}</span>
+            <li
+              key={cmd.name}
+              className="cursor-pointer"
+              onClick={() => setExpanded((v) => v === cmd.name ? null : cmd.name)}
+            >
+              <span className="font-mono text-primary/80">/{cmd.name}</span>
               {cmd.description && (
-                <span className="ml-1.5 text-muted-foreground font-sans line-clamp-1">{cmd.description}</span>
+                <span className={cn(
+                  'ml-1.5 text-muted-foreground font-sans',
+                  expanded === cmd.name ? '' : 'line-clamp-2',
+                )}>
+                  {cmd.description}
+                </span>
               )}
             </li>
           ))}