refactor: remove threads layer, use sessions directly for ACP (#9078)

Co-authored-by: Douwe Osinga <douwe@squareup.com>

ui/desktop/openapi.json

@@ -7720,6 +7720,11 @@
             "format": "int32",
             "nullable": true
           },
+          "archived_at": {
+            "type": "string",
+            "format": "date-time",
+            "nullable": true
+          },
           "conversation": {
             "allOf": [
               {
@@ -7766,6 +7771,10 @@
             "format": "int32",
             "nullable": true
           },
+          "project_id": {
+            "type": "string",
+            "nullable": true
+          },
           "provider_name": {
             "type": "string",
             "nullable": true
@@ -7785,10 +7794,6 @@
           "session_type": {
             "$ref": "#/components/schemas/SessionType"
           },
-          "thread_id": {
-            "type": "string",
-            "nullable": true
-          },
           "total_tokens": {
             "type": "integer",
             "format": "int32",

ui/desktop/src/api/types.gen.ts

@@ -1256,6 +1256,7 @@ export type Session = {
     accumulated_input_tokens?: number | null;
     accumulated_output_tokens?: number | null;
     accumulated_total_tokens?: number | null;
+    archived_at?: string | null;
     conversation?: Conversation | null;
     created_at: string;
     extension_data: ExtensionData;
@@ -1266,11 +1267,11 @@ export type Session = {
     model_config?: ModelConfig | null;
     name: string;
     output_tokens?: number | null;
+    project_id?: string | null;
     provider_name?: string | null;
     recipe?: Recipe | null;
     schedule_id?: string | null;
     session_type?: SessionType;
-    thread_id?: string | null;
     total_tokens?: number | null;
     updated_at: string;
     user_recipe_values?: {