fix: add missing ClientType to InsertChat test params (#24436)

Two `InsertChatParams` blocks in `startworkspace_test.go` were missing
the `ClientType` field. Since the `chat_client_type` enum column is `NOT
NULL`, Postgres rejects the Go zero value (`""`), causing
`TestStartWorkspace` subtests `StoppedWorkspaceReportsAutoUpdate` and
`ManualUpdateRequired` to fail with:

```
pq: invalid input value for enum chat_client_type: ""
```

Closes https://github.com/coder/internal/issues/1471

coderd/x/chatd/chattool/startworkspace_test.go

@@ -431,6 +431,7 @@ func TestStartWorkspace(t *testing.T) {
 		chat, err := db.InsertChat(ctx, database.InsertChatParams{
 			OrganizationID:    org.ID,
 			Status:            database.ChatStatusWaiting,
+			ClientType:        database.ChatClientTypeUi,
 			OwnerID:           user.ID,
 			WorkspaceID:       uuid.NullUUID{UUID: ws.ID, Valid: true},
 			LastModelConfigID: modelCfg.ID,
@@ -495,6 +496,7 @@ func TestStartWorkspace(t *testing.T) {
 		chat, err := db.InsertChat(ctx, database.InsertChatParams{
 			OrganizationID:    org.ID,
 			Status:            database.ChatStatusWaiting,
+			ClientType:        database.ChatClientTypeUi,
 			OwnerID:           user.ID,
 			WorkspaceID:       uuid.NullUUID{UUID: ws.ID, Valid: true},
 			LastModelConfigID: modelCfg.ID,