feat(github): support blobless clone and configurable clone timeout

[fy2ne]

Summary

Addresses #1547.

In \clone-repository.ts, \cloneRepository\ previously hardcoded a 120-second timeout (\2 * 60_000). For large repositories (e.g. \getsentry/static-sites, ~2.1 GB at HEAD) transferring across egress proxies, clones frequently hit 112–115s and trigger an abort coin flip.

This change:

1. Adds \ imeoutSeconds\ (up to 900s, defaulting to 300s / 5 minutes) to \inputSchema\ so callers can configure the clone deadline for heavy repositories.
2. Adds \�lobless\ boolean option (--filter=blob:none) to allow callers to drastically reduce transfer payloads on large repositories.
3. Adds unit test coverage in \clone-repository.test.ts\ for both \ imeoutSeconds\ and \�lobless.

Fixes #1547

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