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/CreateProjectFlow.tsx

@@ -0,0 +1,106 @@
+"use client";
+
+import { useState, useEffect } from "react";
+import { createPortal } from "react-dom";
+import { TypeSelector } from "./TypeSelector";
+import { FreshIdeaSetup } from "./FreshIdeaSetup";
+import { ChatImportSetup } from "./ChatImportSetup";
+import { CodeImportSetup } from "./CodeImportSetup";
+import { MigrateSetup } from "./MigrateSetup";
+
+export type CreationMode = "fresh" | "chat-import" | "code-import" | "migration";
+
+interface CreateProjectFlowProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  workspace: string;
+}
+
+type Step = "select-type" | "setup";
+
+export function CreateProjectFlow({ open, onOpenChange, workspace }: CreateProjectFlowProps) {
+  const [step, setStep] = useState<Step>("select-type");
+  const [mode, setMode] = useState<CreationMode | null>(null);
+
+  useEffect(() => {
+    if (open) {
+      setStep("select-type");
+      setMode(null);
+    }
+  }, [open]);
+
+  useEffect(() => {
+    if (!open) return;
+    const handler = (e: KeyboardEvent) => { if (e.key === "Escape") onOpenChange(false); };
+    window.addEventListener("keydown", handler);
+    return () => window.removeEventListener("keydown", handler);
+  }, [open, onOpenChange]);
+
+  if (!open) return null;
+
+  const handleSelectType = (selected: CreationMode) => {
+    setMode(selected);
+    setStep("setup");
+  };
+
+  const handleBack = () => {
+    setStep("select-type");
+    setMode(null);
+  };
+
+  const setupProps = { workspace, onClose: () => onOpenChange(false), onBack: handleBack };
+
+  return createPortal(
+    <>
+      <style>{`
+        @keyframes vibn-fadeIn { from { opacity:0; } to { opacity:1; } }
+        @keyframes vibn-slideUp { from { opacity:0; transform:translateY(14px); } to { opacity:1; transform:translateY(0); } }
+        @keyframes vibn-spin { to { transform:rotate(360deg); } }
+      `}</style>
+
+      {/* Backdrop */}
+      <div
+        onClick={() => onOpenChange(false)}
+        style={{
+          position: "fixed", inset: 0, zIndex: 50,
+          background: "rgba(26,26,26,0.38)",
+          animation: "vibn-fadeIn 0.15s ease",
+        }}
+      />
+
+      {/* Modal container */}
+      <div style={{
+        position: "fixed", inset: 0, zIndex: 51,
+        display: "flex", alignItems: "center", justifyContent: "center",
+        padding: 24, pointerEvents: "none",
+      }}>
+        <div
+          onClick={e => e.stopPropagation()}
+          style={{
+            background: "#fff", borderRadius: 16,
+            boxShadow: "0 12px 48px rgba(26,26,26,0.16)",
+            width: "100%",
+            maxWidth: step === "select-type" ? 620 : 520,
+            fontFamily: "Outfit, sans-serif",
+            pointerEvents: "all",
+            animation: "vibn-slideUp 0.18s cubic-bezier(0.4,0,0.2,1)",
+            transition: "max-width 0.2s ease",
+            overflow: "hidden",
+          }}
+        >
+          {step === "select-type" && (
+            <TypeSelector
+              onSelect={handleSelectType}
+              onClose={() => onOpenChange(false)}
+            />
+          )}
+          {step === "setup" && mode === "fresh" && <FreshIdeaSetup {...setupProps} />}
+          {step === "setup" && mode === "chat-import" && <ChatImportSetup {...setupProps} />}
+          {step === "setup" && mode === "code-import" && <CodeImportSetup {...setupProps} />}
+          {step === "setup" && mode === "migration" && <MigrateSetup {...setupProps} />}
+        </div>
+      </div>
+    </>,
+    document.body
+  );
+}