feat(server): attachment embedding (#13348)

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

* **New Features**
* Added support for managing "blobs" in Copilot context, including
adding and removing blobs via new GraphQL mutations and UI fields.
* Introduced tracking and querying of blob embeddings within workspaces,
enabling search and similarity matching for blob content.
* Extended Copilot context and workspace APIs, schema, and UI to display
and manage blobs alongside existing documents and files.

* **Bug Fixes**
* Updated context and embedding status logic to handle blobs, ensuring
accurate status reporting and embedding management.

* **Tests**
* Added and updated test cases and snapshots to cover blob embedding
insertion, matching, and removal scenarios.

* **Documentation**
* Updated GraphQL schema and TypeScript types to reflect new
blob-related fields and mutations.

* **Chores**
* Refactored and cleaned up code to support new blob entity and
embedding logic, including renaming and updating internal methods and
types.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/schema.gql

@@ -2,6 +2,11 @@
 # THIS FILE WAS AUTOMATICALLY GENERATED (DO NOT MODIFY)
 # ------------------------------------------------------
 
+input AddContextBlobInput {
+  blobId: String!
+  contextId: String!
+}
+
 input AddContextCategoryInput {
   categoryId: String!
   contextId: String!
@@ -226,6 +231,9 @@ type Copilot {
 }
 
 type CopilotContext {
+  """list blobs in context"""
+  blobs: [CopilotContextBlob!]!
+
   """list collections in context"""
   collections: [CopilotContextCategory!]!
 
@@ -247,16 +255,21 @@ type CopilotContext {
   workspaceId: String!
 }
 
+type CopilotContextBlob {
+  createdAt: SafeInt!
+  id: ID!
+  status: ContextEmbedStatus
+}
+
 type CopilotContextCategory {
   createdAt: SafeInt!
-  docs: [CopilotDocType!]!
+  docs: [CopilotContextDoc!]!
   id: ID!
   type: ContextCategories!
 }
 
 type CopilotContextDoc {
   createdAt: SafeInt!
-  error: String
   id: ID!
   status: ContextEmbedStatus
 }
@@ -281,12 +294,6 @@ type CopilotDocNotFoundDataType {
   docId: String!
 }
 
-type CopilotDocType {
-  createdAt: SafeInt!
-  id: ID!
-  status: ContextEmbedStatus
-}
-
 type CopilotFailedToAddWorkspaceFileEmbeddingDataType {
   message: String!
 }
@@ -1163,6 +1170,9 @@ type Mutation {
   acceptInviteById(inviteId: String!, sendAcceptMail: Boolean @deprecated(reason: "never used"), workspaceId: String @deprecated(reason: "never used")): Boolean!
   activateLicense(license: String!, workspaceId: String!): License!
 
+  """add a blob to context"""
+  addContextBlob(options: AddContextBlobInput!): CopilotContextBlob!
+
   """add a category to context"""
   addContextCategory(options: AddContextCategoryInput!): CopilotContextCategory!
 
@@ -1266,6 +1276,9 @@ type Mutation {
   """Remove user avatar"""
   removeAvatar: RemoveAvatar!
 
+  """remove a blob from context"""
+  removeContextBlob(options: RemoveContextBlobInput!): Boolean!
+
   """remove a category from context"""
   removeContextCategory(options: RemoveContextCategoryInput!): Boolean!
 
@@ -1617,6 +1630,11 @@ type RemoveAvatar {
   success: Boolean!
 }
 
+input RemoveContextBlobInput {
+  blobId: String!
+  contextId: String!
+}
+
 input RemoveContextCategoryInput {
   categoryId: String!
   contextId: String!