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/setup-shared.tsx

@@ -0,0 +1,153 @@
+"use client";
+
+import { ReactNode, CSSProperties } from "react";
+
+export interface SetupProps {
+  workspace: string;
+  onClose: () => void;
+  onBack: () => void;
+}
+
+// Shared modal header
+export function SetupHeader({
+  icon,
+  label,
+  tagline,
+  accent,
+  onBack,
+  onClose,
+}: {
+  icon: string;
+  label: string;
+  tagline: string;
+  accent: string;
+  onBack: () => void;
+  onClose: () => void;
+}) {
+  return (
+    <div style={{ display: "flex", alignItems: "flex-start", justifyContent: "space-between", marginBottom: 28 }}>
+      <div style={{ display: "flex", alignItems: "center", gap: 12 }}>
+        <button
+          onClick={onBack}
+          style={{
+            background: "none", border: "none", cursor: "pointer",
+            color: "#b5b0a6", fontSize: "1rem", padding: "3px 5px",
+            borderRadius: 4, lineHeight: 1, flexShrink: 0,
+          }}
+          onMouseEnter={e => (e.currentTarget.style.color = "#1a1a1a")}
+          onMouseLeave={e => (e.currentTarget.style.color = "#b5b0a6")}
+        >
+          ←
+        </button>
+        <div>
+          <h2 style={{
+            fontFamily: "Newsreader, serif", fontSize: "1.3rem", fontWeight: 400,
+            color: "#1a1a1a", margin: 0, marginBottom: 3,
+          }}>
+            {label}
+          </h2>
+          <p style={{ fontSize: "0.72rem", fontWeight: 600, color: accent, textTransform: "uppercase", letterSpacing: "0.04em", margin: 0 }}>
+            {tagline}
+          </p>
+        </div>
+      </div>
+      <button
+        onClick={onClose}
+        style={{
+          background: "none", border: "none", cursor: "pointer",
+          color: "#b5b0a6", fontSize: "1.2rem", lineHeight: 1,
+          padding: "2px 5px", borderRadius: 4, flexShrink: 0,
+        }}
+        onMouseEnter={e => (e.currentTarget.style.color = "#6b6560")}
+        onMouseLeave={e => (e.currentTarget.style.color = "#b5b0a6")}
+      >
+        ×
+      </button>
+    </div>
+  );
+}
+
+export function FieldLabel({ children }: { children: ReactNode }) {
+  return (
+    <label style={{ display: "block", fontSize: "0.72rem", fontWeight: 600, color: "#6b6560", marginBottom: 6, letterSpacing: "0.02em" }}>
+      {children}
+    </label>
+  );
+}
+
+export function TextInput({
+  value,
+  onChange,
+  placeholder,
+  onKeyDown,
+  autoFocus,
+  inputRef,
+}: {
+  value: string;
+  onChange: (v: string) => void;
+  placeholder?: string;
+  onKeyDown?: (e: React.KeyboardEvent<HTMLInputElement>) => void;
+  autoFocus?: boolean;
+  inputRef?: React.RefObject<HTMLInputElement>;
+}) {
+  const base: CSSProperties = {
+    width: "100%", padding: "11px 14px", marginBottom: 16,
+    borderRadius: 8, border: "1px solid #e0dcd4",
+    background: "#faf8f5", fontSize: "0.9rem",
+    fontFamily: "Outfit, sans-serif", color: "#1a1a1a",
+    outline: "none", boxSizing: "border-box",
+  };
+  return (
+    <input
+      ref={inputRef}
+      type="text"
+      value={value}
+      onChange={e => onChange(e.target.value)}
+      onKeyDown={onKeyDown}
+      placeholder={placeholder}
+      autoFocus={autoFocus}
+      style={base}
+      onFocus={e => (e.currentTarget.style.borderColor = "#1a1a1a")}
+      onBlur={e => (e.currentTarget.style.borderColor = "#e0dcd4")}
+    />
+  );
+}
+
+export function PrimaryButton({
+  onClick,
+  disabled,
+  loading,
+  children,
+}: {
+  onClick: () => void;
+  disabled?: boolean;
+  loading?: boolean;
+  children: ReactNode;
+}) {
+  const active = !disabled && !loading;
+  return (
+    <button
+      onClick={onClick}
+      disabled={!active}
+      style={{
+        width: "100%", padding: "12px",
+        borderRadius: 8, border: "none",
+        background: active ? "#1a1a1a" : "#e0dcd4",
+        color: active ? "#fff" : "#b5b0a6",
+        fontSize: "0.88rem", fontWeight: 600,
+        fontFamily: "Outfit, sans-serif",
+        cursor: active ? "pointer" : "not-allowed",
+        display: "flex", alignItems: "center", justifyContent: "center", gap: 8,
+      }}
+      onMouseEnter={e => { if (active) e.currentTarget.style.opacity = "0.85"; }}
+      onMouseLeave={e => { e.currentTarget.style.opacity = "1"; }}
+    >
+      {loading ? (
+        <>
+          <span style={{ width: 14, height: 14, borderRadius: "50%", border: "2px solid #fff4", borderTopColor: "#fff", animation: "vibn-spin 0.7s linear infinite", display: "inline-block" }} />
+          Creating…
+        </>
+      ) : children}
+    </button>
+  );
+}