flash-mac: also bake github-pat from /api/claude-token response
claude-token netlify fn already returns githubPat alongside the Claude
OAuth token. Bake it to /github-pat in the supplementary cpio archive —
pty.c reads it at child spawn and sets GITHUB_TOKEN so on-device git
push to the GitHub mirror works without SSH setup.
Also broadens the gate so we still build the supplementary cpio when
only githubPat is present (e.g. user saved PAT but never stored Claude
token), and renames the scope log from "claude token: skipped" to
"creds fetch: skipped" since we're fetching both now.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>