fix(desktop): make bundle and updater asset naming configurable

[bavadim]

Summary

This PR removes hard-coded desktop bundle/asset names from macOS bundle scripts and GitHub updater asset lookup by introducing a configurable bundle name via env.

Problem

Desktop customization and rebranding often change app bundle/archive names, but several places still assumed Goose:

• macOS bundle/debug scripts in ui/desktop/package.json
• updater asset lookup and downloaded filename in ui/desktop/src/utils/githubUpdater.ts

That mismatch causes friction and failures in branded distributions (scripts look for Goose.app / updater looks for Goose*.zip while release assets use a custom name).

What changed

• Added GOOSE_BUNDLE_NAME build-time define in ui/desktop/vite.main.config.mts (default: Goose).
• Updated ui/desktop/src/utils/githubUpdater.ts to use GOOSE_BUNDLE_NAME for release asset matching and downloaded file naming.
• Updated macOS scripts in ui/desktop/package.json (bundle:default, bundle:alpha, bundle:intel, debug) to use GOOSE_BUNDLE_NAME instead of hard-coded Goose.

Why this approach

This follows the same configurable-by-env pattern already used for updater/publisher repository settings (GITHUB_OWNER / GITHUB_REPO) and keeps the fix minimally invasive.

Related issues

• Related to Remove hard-coded repo path from auto-updater #6136 (hard-coded repository/path assumptions in updater area)
• Related to goose repository migration tasks #6135 (repo migration tasks including updater and release migration concerns)

Validation

• cd ui/desktop && npm run lint:check
• cd ui/desktop && npm run test:run

Both passed.

AI usage

AI assistance was used to draft and apply code edits; validation was performed by running the checks above.