feat: implement 4 project type flows with unique AI experiences

- New multi-step CreateProjectFlow replaces 2-step modal with TypeSelector
  and 4 setup components (Fresh Idea, Chat Import, Code Import, Migrate)
- overview/page.tsx routes to unique main component per creationMode
- FreshIdeaMain: wraps AtlasChat with post-discovery decision banner
  (Generate PRD vs Plan MVP Test)
- ChatImportMain: 3-stage flow (intake → extracting → review) with
  editable insight buckets (decisions, ideas, questions, architecture, users)
- CodeImportMain: 4-stage flow (input → cloning → mapping → surfaces)
  with architecture map and surface selection
- MigrateMain: 5-stage flow with audit, review, planning, and migration
  plan doc with checkbox-tracked tasks and non-destructive warning banner
- New API routes: analyze-chats, analyze-repo, analysis-status,
  generate-migration-plan (all using Gemini)
- ProjectShell: accepts creationMode prop, filters/renames tabs per type
  (code-import hides PRD, migration hides PRD/Grow/Insights, renames Atlas tab)
- Right panel adapts content based on creationMode

Made-with: Cursor

components/project-creation/ChatImportSetup.tsx

@@ -0,0 +1,84 @@
+"use client";
+
+import { useState } from "react";
+import { useRouter } from "next/navigation";
+import { toast } from "sonner";
+import { SetupHeader, FieldLabel, TextInput, PrimaryButton, type SetupProps } from "./setup-shared";
+
+export function ChatImportSetup({ workspace, onClose, onBack }: SetupProps) {
+  const router = useRouter();
+  const [name, setName] = useState("");
+  const [chatText, setChatText] = useState("");
+  const [loading, setLoading] = useState(false);
+
+  const canCreate = name.trim().length > 0 && chatText.trim().length > 20;
+
+  const handleCreate = async () => {
+    if (!canCreate) return;
+    setLoading(true);
+    try {
+      const res = await fetch("/api/projects/create", {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({
+          projectName: name.trim(),
+          projectType: "web-app",
+          slug: name.toLowerCase().replace(/[^a-z0-9]+/g, "-"),
+          product: { name: name.trim() },
+          creationMode: "chat-import",
+          sourceData: { chatText: chatText.trim() },
+        }),
+      });
+      if (!res.ok) {
+        const err = await res.json();
+        toast.error(err.error || "Failed to create project");
+        return;
+      }
+      const data = await res.json();
+      onClose();
+      router.push(`/${workspace}/project/${data.projectId}/overview`);
+    } catch {
+      toast.error("Something went wrong");
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  return (
+    <div style={{ padding: "32px 36px 36px" }}>
+      <SetupHeader
+        icon="⌁" label="Import Chats" tagline="You've been thinking"
+        accent="#2e5a4a" onBack={onBack} onClose={onClose}
+      />
+
+      <FieldLabel>Project name</FieldLabel>
+      <TextInput
+        value={name}
+        onChange={setName}
+        placeholder="What are you building?"
+        autoFocus
+      />
+
+      <FieldLabel>Paste your chat history</FieldLabel>
+      <textarea
+        value={chatText}
+        onChange={e => setChatText(e.target.value)}
+        placeholder={"Paste conversations from ChatGPT, Claude, Gemini, or any AI tool.\n\nAtlas will extract decisions, ideas, open questions, and architecture notes."}
+        rows={8}
+        style={{
+          width: "100%", padding: "12px 14px", marginBottom: 20,
+          borderRadius: 8, border: "1px solid #e0dcd4",
+          background: "#faf8f5", fontSize: "0.85rem", lineHeight: 1.55,
+          fontFamily: "Outfit, sans-serif", color: "#1a1a1a",
+          outline: "none", resize: "vertical", boxSizing: "border-box",
+        }}
+        onFocus={e => (e.currentTarget.style.borderColor = "#1a1a1a")}
+        onBlur={e => (e.currentTarget.style.borderColor = "#e0dcd4")}
+      />
+
+      <PrimaryButton onClick={handleCreate} disabled={!canCreate} loading={loading}>
+        Extract & analyse →
+      </PrimaryButton>
+    </div>
+  );
+}