Local-node validation references a `validate_local` binary that is not in the repo

## Background

The documented build pipeline gates contract work on local-node validation before any frontend work begins. That step is invoked as a fixed command in three places, the parent agentic-template `CLAUDE.md`, this repo's `CLAUDE.md`, and the `local-node-validation` skill:

```
cargo run --bin validate_local --release
```

## Problem

There is no `validate_local` binary in the repo. The only binary tracked under `integration/src/bin/` is `increment_count.rs`. So the headline gate of the pipeline points at a binary that does not exist: an agent or a developer following the documented flow hits a missing-target error at the exact step meant to validate against a real node. It is also unclear whether `validate_local` was dropped, renamed, or was always meant to be written per project; either way, the docs and the skill present it as a ready command.

## Proposed Solution

Pick one and make the docs and the skill match:

- `validate_local` is a fixed command => ship a real `integration/src/bin/validate_local.rs` (modeled on `increment_count.rs`) that runs the counter flow against a local node and asserts state, so the documented command works out of the box.
- `validate_local` is per project => re-specify the docs and the `local-node-validation` skill to instruct writing a `validate_local` binary for your own contract, using `increment_count.rs` as the model, rather than presenting it as an existing command.

The first keeps the pipeline runnable as written; the second is honest about the template being a starting point. Any preference on direction?

查看引用 validate_local 二進位檔案的三個位置：CLAUDE.md 檔案和 local-node-validation 技能。檢查位於 integration/src/bin/increment_count.rs 的現有二進位檔案以理解其模式。決定是建立一個新的 validate_local.rs 二進位檔案，還是更新文件以澄清這是一個按專案執行的任務。透過執行建置管線步驟來測試所選解決方案。

由索引模型根據 Issue 內容生成。