refactor(webapp): use the branded run-ops legacy handle in cancelTaskRun

Swap cancelTaskRun's V1 finalize writes from runOpsLegacyPrisma (control-plane
typed, needed a runops-legacy-ok annotation) to the branded runOpsLegacyPrismaClient,
which the guard classifies as run-ops. Same legacy writer at runtime; drops the two
annotations and their baseline entries. Matches the existing legacyWriter usage.

Author: d-cs

apps/webapp/app/v3/runOpsMigration/track1-baseline.json

@@ -75,7 +75,7 @@
     "write": 0,
     "read": 4,
     "files": 1,
-    "legacyAnnotations": 2
+    "legacyAnnotations": 0
   },
   "violations": [
     {
@@ -115,18 +115,5 @@
       "snippet": "const legacyRows = (await legacyReplica.taskRun.findMany({"
     }
   ],
-  "legacyAnnotations": [
-    {
-      "file": "apps/webapp/app/v3/services/cancelTaskRun.server.ts",
-      "line": 48,
-      "reason": "bulk-action tag on a historical V1 run (legacy-resident)",
-      "receiver": "runOpsLegacyPrisma"
-    },
-    {
-      "file": "apps/webapp/app/v3/services/cancelTaskRun.server.ts",
-      "line": 57,
-      "reason": "finalize (cancel) a historical V1 run (legacy-resident)",
-      "receiver": "runOpsLegacyPrisma"
-    }
-  ]
+  "legacyAnnotations": []
 }

apps/webapp/app/v3/services/cancelTaskRun.server.ts

@@ -1,5 +1,5 @@
 import { RunEngineVersion, type TaskRun } from "@trigger.dev/database";
-import { runOpsLegacyPrisma } from "~/db.server";
+import { runOpsLegacyPrismaClient } from "~/db.server";
 import { engine } from "../runEngine.server";
 import { isCancellableRunStatus } from "../taskStatus";
 import { BaseService } from "./baseService.server";
@@ -44,17 +44,15 @@ export class CancelTaskRunService extends BaseService {
     // DB row directly. Never throw here: the cancel route returns 500 on any throw.
     if (!isCancellableRunStatus(taskRun.status)) {
       if (options?.bulkActionId) {
-        // runops-legacy-ok: bulk-action tag on a historical V1 run (legacy-resident)
-        await runOpsLegacyPrisma.taskRun.update({
+        await runOpsLegacyPrismaClient.taskRun.update({
           where: { id: taskRun.id },
           data: { bulkActionGroupIds: { push: options.bulkActionId } },
         });
       }
       return { id: taskRun.id, alreadyFinished: true };
     }
 
-    // runops-legacy-ok: finalize (cancel) a historical V1 run (legacy-resident)
-    await runOpsLegacyPrisma.taskRun.update({
+    await runOpsLegacyPrismaClient.taskRun.update({
       where: { id: taskRun.id },
       data: {
         status: "CANCELED",