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-update.ts

@@ -0,0 +1,57 @@
+import { join } from "path"
+import type { OhMyOpenCodeConfig } from "../../config/schema"
+import { TaskUpdateInputSchema, TaskObjectSchema } from "./types"
+import { acquireLock, getTaskDir, readJsonSafe, writeJsonAtomic } from "../../features/claude-tasks/storage"
+import { parseTaskId } from "./task-id-validator"
+
+export async function handleUpdate(
+  args: Record<string, unknown>,
+  config: Partial<OhMyOpenCodeConfig>
+): Promise<string> {
+  const validatedArgs = TaskUpdateInputSchema.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`)
+    const task = readJsonSafe(taskPath, TaskObjectSchema)
+
+    if (!task) {
+      return JSON.stringify({ error: "task_not_found" })
+    }
+
+    if (validatedArgs.subject !== undefined) {
+      task.subject = validatedArgs.subject
+    }
+    if (validatedArgs.description !== undefined) {
+      task.description = validatedArgs.description
+    }
+    if (validatedArgs.status !== undefined) {
+      task.status = validatedArgs.status
+    }
+    if (validatedArgs.addBlockedBy !== undefined) {
+      task.blockedBy = [...task.blockedBy, ...validatedArgs.addBlockedBy]
+    }
+    if (validatedArgs.repoURL !== undefined) {
+      task.repoURL = validatedArgs.repoURL
+    }
+    if (validatedArgs.parentID !== undefined) {
+      task.parentID = validatedArgs.parentID
+    }
+
+    const validatedTask = TaskObjectSchema.parse(task)
+    writeJsonAtomic(taskPath, validatedTask)
+
+    return JSON.stringify({ task: validatedTask })
+  } finally {
+    lock.release()
+  }
+}