Release: ship okf-windows-x64.exe alongside the linux and macOS binaries

## What and why

conceptadev/okf-profile is making the Profile tooling usable without a Dart SDK (okf-profile#53): a Claude Code plugin registers `okf mcp knowledge`, and one-line installers put `okf` and `okfp` on `PATH` on macOS, Linux, and Windows. `okfp` gains `okfp-windows-x64.exe` in that work; the Windows installer then needs the matching `okf` binary from this repository's releases.

## Ask

Add a Windows row to `tool/ci/platforms.tsv` so releases attach `okf-windows-x64.exe`:

```
Windows X64 windows-latest okf-windows-x64.exe
```

On the okf-profile side the grinder needed no change: cli_pkg's `pkg-compile-native` writes `build/.native` on every platform, the build task copies it to `$ASSET`, and the `chmod` is already guarded on Windows. `verify-engine-version.sh` is invoked through `bash` explicitly, so it runs under the runner's git-bash. The same should hold here since the release tooling is the same shape.

## Acceptance

- [ ] A release tag attaches `okf-windows-x64.exe`; `./okf-windows-x64.exe --version` prints `okf ` on `windows-latest`.
- [ ] `gh release verify-asset` succeeds for it (immutable releases are already on here).

Blocks the Windows acceptance criterion of okf-profile#53.

Start with tool/ci/platforms.tsv and compare the existing Linux and macOS rows with the release tooling that consumes this table. Validate a tagged release on windows-latest, confirm that okf-windows-x64.exe is attached and executable, and run ./okf-windows-x64.exe --version plus gh release verify-asset.

Written by the indexing model from the issue text.