Run freebuff Windows build + smoke on every push

The tree-sitter wasm regression that crashed freebuff 0.0.62 only
manifested on real Windows. CI was Linux-only, macOS dev machines
behaved fine, and the Windows binary was only built+smoked at release
time (cli-release-build.yml). So the bug shipped twice before being
caught by user reports.

Add a windows-latest job to freebuff-e2e.yml that builds the freebuff
binary natively on Windows and runs the long smoke test against it.
The full tmux-based e2e matrix can't follow — Windows runners don't
ship tmux, and porting tmuxStart/tmuxSend would be substantial — but
smoke-binary.ts catches the failure mode that bit us: it spawns the
binary, waits long enough for the late renderer-cleanup rejection
handler to fire, and asserts both that no fatal markers appeared and
that the boot screen actually rendered.

Mirrors the Windows-specific bits from cli-release-build.yml's
build-windows-binary job: explicit `bun install --cwd cli` and the
@opentui workspace symlink fix, both needed because bun workspace
linking doesn't work reliably on Windows runners.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>