feat(artifact): add admin RPCs for knowledge base consolidation migration (#723)

**Because**

- The KB consolidation migration (convert000070) needs to move files
from legacy/duplicate KBs to the primary default KB
- Files can belong to multiple KBs (many-to-many relationship via
junction table)
- After consolidating files, legacy KBs need to be deleted without
affecting the files themselves

**This commit**

- Adds `AddFilesToKnowledgeBaseAdmin` RPC that accepts file resource
names (`namespaces/{namespace}/files/{file}`) and adds associations to a
target KB, skipping duplicates
- Adds `DeleteKnowledgeBaseAdmin` RPC that force-deletes a KB even if it
has file associations (files remain orphaned until re-associated)
- Adds corresponding request/response message types with proper AIP
annotations (`google.api.resource_reference`,
`google.api.field_behavior`)

Author: pinglin

artifact/v1alpha/artifact_private_service.proto

@@ -125,4 +125,18 @@ service ArtifactPrivateService {
 
   // Reset knowledge base embeddings (admin only)
   rpc ResetKnowledgeBaseEmbeddingsAdmin(ResetKnowledgeBaseEmbeddingsAdminRequest) returns (ResetKnowledgeBaseEmbeddingsAdminResponse);
+
+  // Add files to knowledge base (admin only)
+  //
+  // Adds file associations to a target knowledge base by file UIDs.
+  // Files can belong to multiple KBs (many-to-many relationship).
+  // Files that already exist in the target KB are skipped (no duplicates).
+  rpc AddFilesToKnowledgeBaseAdmin(AddFilesToKnowledgeBaseAdminRequest) returns (AddFilesToKnowledgeBaseAdminResponse);
+
+  // Delete knowledge base (admin only)
+  //
+  // Force deletes a knowledge base even if it contains files. The files remain
+  // in the file table but lose their KB association (orphaned). Used during
+  // KB consolidation migrations after files have been moved to another KB.
+  rpc DeleteKnowledgeBaseAdmin(DeleteKnowledgeBaseAdminRequest) returns (DeleteKnowledgeBaseAdminResponse);
 }

artifact/v1alpha/knowledge_base.proto

@@ -334,3 +334,46 @@ message ResetKnowledgeBaseEmbeddingsAdminResponse {
   // Number of files that will be re-embedded.
   int32 files_to_reembed = 2 [(google.api.field_behavior) = OUTPUT_ONLY];
 }
+
+// MoveFilesToKnowledgeBaseAdminRequest represents a request to move files from
+// source knowledge bases to a target knowledge base (admin only).
+// Adds file associations to a knowledge base (admin only).
+// Files can belong to multiple KBs (many-to-many relationship).
+message AddFilesToKnowledgeBaseAdminRequest {
+  // The resource name of the target knowledge base to add files to.
+  // Format: `namespaces/{namespace}/knowledge-bases/{knowledge_base}`
+  string target_knowledge_base = 1 [
+    (google.api.field_behavior) = REQUIRED,
+    (google.api.resource_reference) = {type: "api.instill.tech/KnowledgeBase"}
+  ];
+  // The resource names of files to add to the target knowledge base.
+  // Format: `namespaces/{namespace}/files/{file}`
+  // Files that already exist in the target KB are skipped (no duplicates).
+  repeated string files = 2 [
+    (google.api.field_behavior) = REQUIRED,
+    (google.api.resource_reference) = {type: "api.instill.tech/File"}
+  ];
+}
+
+// AddFilesToKnowledgeBaseAdminResponse represents a response for adding files.
+message AddFilesToKnowledgeBaseAdminResponse {
+  // Number of files added to the target knowledge base.
+  int32 files_added = 1 [(google.api.field_behavior) = OUTPUT_ONLY];
+}
+
+// DeleteKnowledgeBaseAdminRequest represents a request to delete a knowledge
+// base (admin only). This force deletes the KB even if it contains files.
+// Files are NOT deleted - they remain orphaned (no KB association).
+message DeleteKnowledgeBaseAdminRequest {
+  // The resource name of the knowledge base to delete.
+  // Format: `namespaces/{namespace}/knowledge-bases/{knowledge_base}`
+  string name = 1 [
+    (google.api.field_behavior) = REQUIRED,
+    (google.api.resource_reference) = {type: "api.instill.tech/KnowledgeBase"}
+  ];
+}
+
+// DeleteKnowledgeBaseAdminResponse represents a response for deleting a KB.
+message DeleteKnowledgeBaseAdminResponse {
+  // Empty response on success.
+}