#7255 fix(connectors): stop hydration after rate limits

Summary

• stop deferred connector hydration after a structured upstream rate limit so later batches do not amplify one provider throttle into per-document failures
• preserve the typed provider error and retry delay for the existing connector backoff scheduler while leaving ordinary document failures isolated
• use GitHub’s documented object media type for file metadata and a byte-bounded raw blob stream for large content, surfacing non-404 failures and oversized blobs explicitly
• add connector and sync-engine regressions for the exact rate-limit, large-file, absence, permission, and byte-cap behaviors

Testing

• bun run --cwd apps/sim test -- connectors/github/github.test.ts lib/knowledge/documents/utils.test.ts lib/knowledge/connectors/sync-engine.test.ts
• bun run --cwd apps/sim type-check
• bun run agent-stream-docs:generate
• bun run skills:sync
• bun run lint
• bun run apps/sim/scripts/check-block-registry.ts origin/staging
• bun run check:audits