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/frontend/core/package.json

@@ -16,7 +16,7 @@
     "@affine/i18n": "workspace:*",
     "@affine/templates": "workspace:*",
     "@affine/track": "workspace:*",
-    "@blocksuite/affine": "0.17.18",
+    "@blocksuite/affine": "0.17.19",
     "@blocksuite/icons": "2.1.68",
     "@dnd-kit/core": "^6.1.0",
     "@dnd-kit/modifiers": "^7.0.0",
@@ -27,6 +27,7 @@
     "@floating-ui/dom": "^1.6.5",
     "@juggle/resize-observer": "^3.4.0",
     "@marsidev/react-turnstile": "^1.0.0",
+    "@preact/signals-core": "^1.8.0",
     "@radix-ui/react-collapsible": "^1.0.3",
     "@radix-ui/react-dialog": "^1.0.5",
     "@radix-ui/react-popover": "^1.0.7",