feat: multipart blob sync support (#14138)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Flexible blob uploads: GRAPHQL, presigned, and multipart flows with
per‑part URLs, abort/complete operations, presigned proxy endpoints, and
nightly cleanup of expired pending uploads.

* **API / Schema**
* GraphQL additions: new types, mutations, enum and error to manage
upload lifecycle (create, complete, abort, get part URL).

* **Database**
* New blob status enum and columns (status, upload_id); listing now
defaults to completed blobs.

* **Localization**
  * Added user-facing message: "Blob is invalid."

* **Tests**
* Expanded unit and end‑to‑end coverage for upload flows, proxy
behavior, multipart and provider integrations.

<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/schema.gql

@@ -96,6 +96,41 @@ type BlobNotFoundDataType {
   spaceId: String!
 }
 
+type BlobUploadInit {
+  alreadyUploaded: Boolean
+  blobKey: String!
+  expiresAt: DateTime
+  headers: JSONObject
+  method: BlobUploadMethod!
+  partSize: Int
+  uploadId: String
+  uploadUrl: String
+  uploadedParts: [BlobUploadedPart!]
+}
+
+"""Blob upload method"""
+enum BlobUploadMethod {
+  GRAPHQL
+  MULTIPART
+  PRESIGNED
+}
+
+type BlobUploadPart {
+  expiresAt: DateTime
+  headers: JSONObject
+  uploadUrl: String!
+}
+
+input BlobUploadPartInput {
+  etag: String!
+  partNumber: Int!
+}
+
+type BlobUploadedPart {
+  etag: String!
+  partNumber: Int!
+}
+
 enum ChatHistoryOrder {
   asc
   desc
@@ -659,6 +694,7 @@ enum ErrorNames {
   ALREADY_IN_SPACE
   AUTHENTICATION_REQUIRED
   BAD_REQUEST
+  BLOB_INVALID
   BLOB_NOT_FOUND
   BLOB_QUOTA_EXCEEDED
   CANNOT_DELETE_ACCOUNT_WITH_OWNED_TEAM_WORKSPACE
@@ -1194,6 +1230,7 @@ type MissingOauthQueryParameterDataType {
 }
 
 type Mutation {
+  abortBlobUpload(key: String!, uploadId: String!, workspaceId: String!): Boolean!
   acceptInviteById(inviteId: String!, sendAcceptMail: Boolean @deprecated(reason: "never used"), workspaceId: String @deprecated(reason: "never used")): Boolean!
   activateLicense(license: String!, workspaceId: String!): License!
 
@@ -1223,6 +1260,8 @@ type Mutation {
 
   """Cleanup sessions"""
   cleanupCopilotSession(options: DeleteSessionInput!): [String!]!
+  completeBlobUpload(key: String!, parts: [BlobUploadPartInput!], uploadId: String, workspaceId: String!): String!
+  createBlobUpload(key: String!, mime: String!, size: Int!, workspaceId: String!): BlobUploadInit!
 
   """Create change password url"""
   createChangePasswordUrl(callbackUrl: String!, userId: String!): String!
@@ -1275,6 +1314,7 @@ type Mutation {
   forkCopilotSession(options: ForkChatSessionInput!): String!
   generateLicenseKey(sessionId: String!): String!
   generateUserAccessToken(input: GenerateAccessTokenInput!): RevealedAccessToken!
+  getBlobUploadPartUrl(key: String!, partNumber: Int!, uploadId: String!, workspaceId: String!): BlobUploadPart!
   grantDocUserRoles(input: GrantDocUserRolesInput!): Boolean!
   grantMember(permission: Permission!, userId: String!, workspaceId: String!): Boolean!