Fix AI chat streaming persistence when command menu closes (#14854)

Closes [#1583](https://github.com/twentyhq/core-team-issues/issues/1583)


- Removed `messageId` column from `File` table and its references in
code (unrelated to this PR)
- Updated AI chat to use React Context API with persistent provider in
`CommandMenuContainer`
- Converted all AI chat component states to regular Recoil atoms (no
instance context needed)

---------

Co-authored-by: Félix Malfait <felix@twenty.com>

packages/twenty-front/src/generated/graphql.ts

@@ -70,7 +70,6 @@ export type Agent = {
 export type AgentChatMessage = {
   __typename?: 'AgentChatMessage';
   createdAt: Scalars['DateTime'];
-  files: Array<File>;
   id: Scalars['UUID'];
   parts: Array<AgentChatMessagePart>;
   role: Scalars['String'];
@@ -1281,7 +1280,6 @@ export type File = {
   createdAt: Scalars['DateTime'];
   fullPath: Scalars['String'];
   id: Scalars['UUID'];
-  messageId?: Maybe<Scalars['UUID']>;
   name: Scalars['String'];
   size: Scalars['Float'];
   type: Scalars['String'];