feat: load Atlas discovery history into CooChat sidebar

Eliminates the two-chat experience on the overview page:

- CooChat now pre-loads Atlas conversation history on mount, showing
  the full discovery conversation in the left panel. Atlas messages
  render with a blue "A" avatar; COO messages use the dark "◈" icon.
  A "Discovery · COO" divider separates historical from new messages.
- FreshIdeaMain detects when a PRD already exists and replaces the
  duplicate AtlasChat with a clean completion view ("Discovery complete")
  that links to the PRD and Build pages. Atlas chat only shows when
  discovery is still in progress.

Made-with: Cursor

components/project-main/FreshIdeaMain.tsx

@@ -3,6 +3,7 @@
 import { useEffect, useState } from "react";
 import { AtlasChat } from "@/components/AtlasChat";
 import { useRouter, useParams } from "next/navigation";
+import Link from "next/link";
 
 const DISCOVERY_PHASES = [
   "big_picture",
@@ -27,8 +28,15 @@ export function FreshIdeaMain({ projectId, projectName }: FreshIdeaMainProps) {
   const [allDone, setAllDone] = useState(false);
   const [prdLoading, setPrdLoading] = useState(false);
   const [dismissed, setDismissed] = useState(false);
+  const [hasPrd, setHasPrd] = useState(false);
 
   useEffect(() => {
+    // Check if PRD already exists on the project
+    fetch(`/api/projects/${projectId}`)
+      .then(r => r.json())
+      .then(d => { if (d.project?.prd) setHasPrd(true); })
+      .catch(() => {});
+
     const poll = () => {
       fetch(`/api/projects/${projectId}/save-phase`)
         .then(r => r.json())
@@ -59,6 +67,62 @@ export function FreshIdeaMain({ projectId, projectName }: FreshIdeaMainProps) {
     router.push(`/${workspace}/project/${projectId}/build`);
   };
 
+  // Once the PRD exists, show a clean "done" state in the main panel.
+  // The Atlas conversation history lives in the left CooChat sidebar.
+  if (hasPrd) {
+    return (
+      <div style={{
+        height: "100%", display: "flex", flexDirection: "column",
+        alignItems: "center", justifyContent: "center",
+        fontFamily: "Outfit, sans-serif", padding: "32px",
+      }}>
+        <div style={{
+          maxWidth: 420, textAlign: "center",
+          display: "flex", flexDirection: "column", alignItems: "center", gap: 20,
+        }}>
+          <div style={{
+            width: 48, height: 48, borderRadius: 14, background: "#1a1a1a",
+            display: "flex", alignItems: "center", justifyContent: "center",
+            fontSize: "1.2rem", color: "#fff",
+          }}>✦</div>
+          <div>
+            <div style={{ fontSize: "1.05rem", fontWeight: 700, color: "#1a1a1a", marginBottom: 6 }}>
+              Discovery complete
+            </div>
+            <div style={{ fontSize: "0.82rem", color: "#6b6560", lineHeight: 1.65 }}>
+              Your PRD is saved. The full discovery conversation is in the left panel — talk to your COO to plan what to build next.
+            </div>
+          </div>
+          <div style={{ display: "flex", gap: 10 }}>
+            <Link
+              href={`/${workspace}/project/${projectId}/prd`}
+              style={{
+                padding: "10px 20px", borderRadius: 8, border: "none",
+                background: "#1a1a1a", color: "#fff",
+                fontSize: "0.82rem", fontWeight: 600,
+                textDecoration: "none", display: "inline-block",
+              }}
+            >
+              View PRD →
+            </Link>
+            <Link
+              href={`/${workspace}/project/${projectId}/build`}
+              style={{
+                padding: "10px 20px", borderRadius: 8,
+                border: "1px solid #e8e4dc",
+                background: "#fff", color: "#1a1a1a",
+                fontSize: "0.82rem", fontWeight: 500,
+                textDecoration: "none", display: "inline-block",
+              }}
+            >
+              Go to Build
+            </Link>
+          </div>
+        </div>
+      </div>
+    );
+  }
+
   return (
     <div style={{ height: "100%", display: "flex", flexDirection: "column", position: "relative" }}>
       {/* Decision banner — shown when all 6 phases are saved */}