feat(task): refactor to Claude Code style individual tools

- Split unified Task tool into individual tools (TaskCreate, TaskGet, TaskList, TaskUpdate)
- Update schema to Claude Code field names (subject, blockedBy, blocks, activeForm, owner, metadata)
- Add OpenCode Todo API sync layer (todo-sync.ts)
- Implement Todo sync on task create/update for continuation enforcement
- Add comprehensive tests for all tools (96 tests total)
- Update AGENTS.md documentation

Breaking Changes:
- Field names changed: title→subject, dependsOn→blockedBy, open→pending
- Tool names changed: task→task_create, task_get, task_list, task_update

Closes: todo-continuation-enforcer now sees Task-created items

src/tools/task/index.ts

@@ -1,5 +1,6 @@
-export { createTask } from "./task"
 export { createTaskCreateTool } from "./task-create"
+export { createTaskGetTool } from "./task-get"
+export { createTaskList } from "./task-list"
 export { createTaskUpdateTool } from "./task-update"
 export { syncTaskToTodo, syncAllTasksToTodos } from "./todo-sync"
 export type { TaskObject, TaskStatus, TaskCreateInput, TaskListInput, TaskGetInput, TaskUpdateInput, TaskDeleteInput } from "./types"