refactor: move chat block to affine (#8368)

[BS-898](https://linear.app/affine-design/issue/BS-898/move-ai-chat-block-to-affine)

Should be merged after https://github.com/toeverything/blocksuite/pull/8420 merged and bumped.

packages/common/env/package.json

@@ -3,7 +3,7 @@
   "private": true,
   "type": "module",
   "devDependencies": {
-    "@blocksuite/affine": "0.17.18",
+    "@blocksuite/affine": "0.17.19",
     "vitest": "2.1.1"
   },
   "exports": {