fix(build): bun-on-Windows compatibility for the package.json build script

[mikepsinn]

Problem

bun run build fails on Windows + Bun 1.3 because three things in the current build script don't parse in bun's POSIX shell on Windows:

1. Brace-grouped redirect: { git rev-parse HEAD 2>/dev/null || true; } > browse/dist/.version (and two more for design/dist, make-pdf/dist). Bun on Windows treats { as a literal command and errors with bun: command not found: {.
2. Subshell-grouped redirect: I tried ( ... ) > FILE as a fix — bun errors with Subshells with redirections are currently not supported.
3. Glob-no-match cleanup: (rm -f .*.bun-build || true) fails BEFORE the || true has a chance to catch the no-match, because bun's glob rejection happens at parse time.

Net effect: ./setup on Windows logs a real-looking build then dies with error: script "build" exited with code 1, leaving .version files unwritten.

Fix

1. Replace the three brace-grouped git rev-parse HEAD ... > .version constructs with a single node scripts/write-versions.mjs invocation. Same semantics — write the current HEAD SHA into browse/dist/.version, design/dist/.version, make-pdf/dist/.version, with a try/catch fallback when not in a git repo. Cross-platform.
2. Remove the final (rm -f .*.bun-build || true) cleanup; bun on Windows can't parse it and the build tool already cleans its temp files on success.

scripts/write-versions.mjs uses fileURLToPath(new URL('..', import.meta.url)) (portable to older Node) rather than import.meta.dirname (newer-Node-only).

Verified

• Windows 11 + Bun 1.3.6 + Node 22: bun run build now completes and produces browse.exe, find-browse.exe, design.exe, pdf.exe, gstack-global-discover.exe, server-node.mjs, and the three .version files (containing the current HEAD SHA).
• macOS/Linux behavior unchanged — the brace-grouped redirects were just version-stamp writes, which the node helper now does cross-platform.

Notes

• I'm a new gstack user (installed yesterday on Windows). Hitting this build failure was my first 30 seconds with gstack — figured upstreaming was less hassle for everyone than carrying a local fork.
• Happy to adjust the patch shape if you'd rather solve this differently (e.g. a scripts/build.sh that runs the brace-grouped writes via bash instead of bun's shell). Tell me what you'd prefer and I'll re-shape.

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