P1 exit: chat UI, sessions column, agent create — 11 E2E journeys green

- Stream layer: incremental SSE parser tested against bytes captured from
  the REAL gateway (chunking-independent, UTF-8-safe, heartbeat-tolerant);
  Zod gateway event schemas; pure transcript reducer (optimistic send,
  delta streaming, step traces, resume dedupe, error states)
- Same-origin /api proxy route: httpOnly cookie -> bearer, unbuffered SSE
  passthrough; NuqsAdapter in root layout
- Chat workspace: route /claws/{id}/chat/{key} (RSC history + settings),
  WelcomeState with suggested prompts, MessageList (right user bubbles,
  left agent messages, blink caret), collapsible StepTrace, Composer
  (Enter sends, Shift+Enter newline)
- SessionsColumn in 208px SlidePanel (?sessions=1): search, relative
  times, active coral border, new session; /claws/{id} resumes latest or
  opens fresh; minimal create-claw form; rail + button and roster links
- P1 exit E2E: scripted reply streams, tool step trace survives reload,
  separate transcripts across sessions with column switching, create claw
  and chat immediately

83 Rust + 56 frontend unit/component tests + 11 Playwright journeys.

Co-Authored-By: Claude Fable 5 <[email protected]>

frontend/src/components/chat/WelcomeState.tsx

@@ -0,0 +1,42 @@
+import type { Agent } from "@/lib/api/schemas";
+import { Avatar } from "@/components/ui/Avatar";
+
+const SUGGESTED_PROMPTS = [
+  "Create a daily briefing",
+  "Write a report",
+  "Make a presentation",
+  "What can you do?",
+];
+
+/** Empty-session welcome (§5a). */
+export function WelcomeState({
+  agent,
+  onPick,
+}: {
+  agent: Agent;
+  onPick: (prompt: string) => void;
+}) {
+  return (
+    <div className="flex flex-1 flex-col items-center justify-center gap-3 px-4 motion-safe:animate-[fade-up_var(--duration-normal)_var(--ease-app)]">
+      <Avatar name={agent.name} accent={agent.accent} size="lg" />
+      <h2 className="text-center text-xl font-semibold tracking-tight">
+        Hi, I&apos;m {agent.name}. What can I help with?
+      </h2>
+      <p className="text-sm text-muted-foreground">
+        {agent.job_title} · Shared with your team
+      </p>
+      <div className="flex max-w-md flex-wrap justify-center gap-2 pt-2">
+        {SUGGESTED_PROMPTS.map((prompt) => (
+          <button
+            key={prompt}
+            type="button"
+            onClick={() => onPick(prompt)}
+            className="rounded-(--radius-button) border border-border bg-subtle px-3 py-1.5 text-xs text-muted-foreground hover:border-accent hover:text-foreground"
+          >
+            {prompt}
+          </button>
+        ))}
+      </div>
+    </div>
+  );
+}