refactor(task-tool): split task.ts into per-action modules

Extract CRUD actions into dedicated modules:
- task-action-create.ts, task-action-get.ts
- task-action-list.ts, task-action-update.ts, task-action-delete.ts
- task-id-validator.ts: ID validation logic

src/tools/task/task-action-delete.ts

@@ -0,0 +1,36 @@
+import { existsSync, unlinkSync } from "fs"
+import { join } from "path"
+import type { OhMyOpenCodeConfig } from "../../config/schema"
+import { TaskDeleteInputSchema } from "./types"
+import { acquireLock, getTaskDir } from "../../features/claude-tasks/storage"
+import { parseTaskId } from "./task-id-validator"
+
+export async function handleDelete(
+  args: Record<string, unknown>,
+  config: Partial<OhMyOpenCodeConfig>
+): Promise<string> {
+  const validatedArgs = TaskDeleteInputSchema.parse(args)
+  const taskId = parseTaskId(validatedArgs.id)
+  if (!taskId) {
+    return JSON.stringify({ error: "invalid_task_id" })
+  }
+  const taskDir = getTaskDir(config)
+  const lock = acquireLock(taskDir)
+
+  if (!lock.acquired) {
+    return JSON.stringify({ error: "task_lock_unavailable" })
+  }
+
+  try {
+    const taskPath = join(taskDir, `${taskId}.json`)
+
+    if (!existsSync(taskPath)) {
+      return JSON.stringify({ error: "task_not_found" })
+    }
+
+    unlinkSync(taskPath)
+    return JSON.stringify({ success: true })
+  } finally {
+    lock.release()
+  }
+}