fix(dev): add .exe to Windows sidecar stub paths

[sumit-m]

Summary

Appends .exe to the sidecar stub filenames on Windows so _ensure-sidecar-stubs produces the names Tauri's externalBin validation expects.

On Windows the host triple is x86_64-pc-windows-msvc and Tauri looks for binaries/<bin>-x86_64-pc-windows-msvc.exe. The recipe creates the stubs without the suffix, so Tauri rejects them and every recipe depending on _ensure-sidecar-stubs — dev, desktop, desktop-standalone, desktop-staging — fails before the app starts.

Three lines, and a no-op on every other platform: EXT stays empty unless the triple contains windows.

Related issue

Fixes #2492.

Two open PRs touch the same recipe, and I have not seen a maintainer signal which should land first:

• fix(desktop): Windows sidecar stubs, managed Node, onboarding scroll #2496 contains this same .exe fix, bundled with a managed-Node install and an onboarding scroll fix. It is currently CONFLICTING and has been unreviewed since 2026-07-27. This PR isolates just the .exe change so it can be reviewed on its own; if fix(desktop): Windows sidecar stubs, managed Node, onboarding scroll #2496 is preferred, close this one.
• fix(desktop): stage real sidecar binaries in _ensure-sidecar-stubs #2597 rewrites the same loop to stage real binaries over the stubs (a different bug — os error 13). It keeps the extensionless name, so it does not fix Windows and would conflict textually with this change. Whichever merges first, the other is a small rebase — happy to do that on this branch.

Testing

Verified on Windows 11 (x86_64-pc-windows-msvc, Git Bash):

$ rm -rf desktop/src-tauri/binaries && just _ensure-sidecar-stubs
$ ls desktop/src-tauri/binaries/
buzz-acp-x86_64-pc-windows-msvc.exe
buzz-agent-x86_64-pc-windows-msvc.exe
buzz-dev-mcp-x86_64-pc-windows-msvc.exe
buzz-x86_64-pc-windows-msvc.exe
git-credential-nostr-x86_64-pc-windows-msvc.exe

Before this change the same command produced extensionless files and just dev aborted with binaries\buzz-acp-x86_64-pc-windows-msvc.exe doesn't exist.

Not verified on macOS or Linux — I have no such hardware. The guard is [[ "$TARGET" == *windows* ]], so EXT is empty and the emitted paths are byte-identical to today's on any non-Windows triple.

[Chessing234]

Small and correct — Tauri's Windows externalBin lookup really does want the .exe suffix on the host triple, and leaving EXT empty elsewhere keeps this a no-op on unix. One thing worth a follow-up (not blocking): _ensure-sidecar-stubs still touches empty stubs, so a first just desktop on a clean Windows clone will get past validation and then fail later when the real binaries aren't built. Out of scope for this PR, but related to the same Windows stub path.

[Chessing234]

Approving the sidecar stub fix — minimal, correct, and unblocks every Windows recipe.

[Chessing234]

Approving the Windows sidecar stub extension fix — minimal and unblocks desktop recipes.