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-create.ts

@@ -0,0 +1,46 @@
+import { join } from "path"
+import type { OhMyOpenCodeConfig } from "../../config/schema"
+import type { TaskObject } from "./types"
+import { TaskCreateInputSchema, TaskObjectSchema } from "./types"
+import {
+  acquireLock,
+  generateTaskId,
+  getTaskDir,
+  writeJsonAtomic,
+} from "../../features/claude-tasks/storage"
+
+export async function handleCreate(
+  args: Record<string, unknown>,
+  config: Partial<OhMyOpenCodeConfig>,
+  context: { sessionID: string }
+): Promise<string> {
+  const validatedArgs = TaskCreateInputSchema.parse(args)
+  const taskDir = getTaskDir(config)
+  const lock = acquireLock(taskDir)
+
+  if (!lock.acquired) {
+    return JSON.stringify({ error: "task_lock_unavailable" })
+  }
+
+  try {
+    const taskId = generateTaskId()
+    const task: TaskObject = {
+      id: taskId,
+      subject: validatedArgs.subject,
+      description: validatedArgs.description ?? "",
+      status: "pending",
+      blocks: validatedArgs.blocks ?? [],
+      blockedBy: validatedArgs.blockedBy ?? [],
+      repoURL: validatedArgs.repoURL,
+      parentID: validatedArgs.parentID,
+      threadID: context.sessionID,
+    }
+
+    const validatedTask = TaskObjectSchema.parse(task)
+    writeJsonAtomic(join(taskDir, `${taskId}.json`), validatedTask)
+
+    return JSON.stringify({ task: validatedTask })
+  } finally {
+    lock.release()
+  }
+}