fix extension import data sharing with shared store

Critical bug fix: extension-import and get-extension-import were using
separate in-memory Maps, causing 404 errors when fetching import data.

- Create shared utils/import-store.ts module
- Both functions now use same Map instance
- Add logging for debugging
- Note: In-memory storage only works for dev (single process)
Production needs database/Redis/Netlify Blobs

packages/functions/src/extension-import.ts

···
 import type { Handler, HandlerEvent } from '@netlify/functions';
 import type { ExtensionImportRequest, ExtensionImportResponse } from '@atlast/shared';
 import { z } from 'zod';
-import crypto from 'crypto';
+import { storeImport } from './utils/import-store.js';
 
 /**
  * Validation schema for extension import request
···
     sourceUrl: z.string().url()
   })
 });
-
-/**
- * Simple in-memory store for extension imports
- * TODO: Move to database for production
- */
-const importStore = new Map<string, ExtensionImportRequest>();
-
-/**
- * Generate a random import ID
- */
-function generateImportId(): string {
-  return crypto.randomBytes(16).toString('hex');
-}
-
-/**
- * Store import data and return import ID
- */
-function storeImport(data: ExtensionImportRequest): string {
-  const importId = generateImportId();
-  importStore.set(importId, data);
-
-  // Auto-expire after 1 hour
-  setTimeout(() => {
-    importStore.delete(importId);
-  }, 60 * 60 * 1000);
-
-  return importId;
-}
 
 /**
  * Extension import endpoint
···
   }
 };
 
-/**
- * Get import endpoint (helper for import page)
- * GET /extension-import/:id
- */
-export function getImport(importId: string): ExtensionImportRequest | null {
-  return importStore.get(importId) || null;
-}

packages/functions/src/get-extension-import.ts

···
 import type { Handler, HandlerEvent } from '@netlify/functions';
 import type { ExtensionImportRequest } from '@atlast/shared';
-
-/**
- * Import store (shared with extension-import.ts)
- * In production, this would be a database query
- */
-const importStore = new Map<string, ExtensionImportRequest>();
+import { getImport } from './utils/import-store.js';
 
 /**
  * Get extension import by ID
···
       };
     }
 
-    // Get import data
-    const importData = importStore.get(importId);
+    // Get import data from shared store
+    const importData = getImport(importId);
 
     if (!importData) {
       return {

packages/functions/src/utils/import-store.ts

···
+import type { ExtensionImportRequest } from '@atlast/shared';
+import crypto from 'crypto';
+
+/**
+ * Shared in-memory store for extension imports
+ * This is shared between extension-import.ts and get-extension-import.ts
+ *
+ * NOTE: In-memory storage works for development but will NOT work reliably
+ * in production serverless environments where functions are stateless and
+ * can run on different instances.
+ *
+ * For production, replace this with:
+ * - Database (PostgreSQL/Neon)
+ * - Redis/Upstash
+ * - Netlify Blobs
+ */
+const importStore = new Map<string, ExtensionImportRequest>();
+
+/**
+ * Generate a random import ID
+ */
+export function generateImportId(): string {
+  return crypto.randomBytes(16).toString('hex');
+}
+
+/**
+ * Store import data and return import ID
+ */
+export function storeImport(data: ExtensionImportRequest): string {
+  const importId = generateImportId();
+  importStore.set(importId, data);
+
+  console.log(`[ImportStore] Stored import ${importId} with ${data.usernames.length} usernames`);
+
+  // Auto-expire after 1 hour
+  setTimeout(() => {
+    importStore.delete(importId);
+    console.log(`[ImportStore] Expired import ${importId}`);
+  }, 60 * 60 * 1000);
+
+  return importId;
+}
+
+/**
+ * Get import data by ID
+ */
+export function getImport(importId: string): ExtensionImportRequest | null {
+  const data = importStore.get(importId) || null;
+  console.log(`[ImportStore] Get import ${importId}: ${data ? 'found' : 'not found'}`);
+  return data;
+}
+
+/**
+ * Delete import data by ID
+ */
+export function deleteImport(importId: string): boolean {
+  const result = importStore.delete(importId);
+  console.log(`[ImportStore] Delete import ${importId}: ${result ? 'success' : 'not found'}`);
+  return result;
+}
+
+/**
+ * Get store stats (for debugging)
+ */
+export function getStoreStats(): { count: number; ids: string[] } {
+  return {
+    count: importStore.size,
+    ids: Array.from(importStore.keys())
+  };
+}