fix(github): prefer repository permission alternatives

[realmroot]

Summary

• prefer a satisfied repository-domain permission alternative over metadata-only fallback
• preserve transparent GitHub API proxying and GitHub App permission boundaries
• document the operation permission resolution rule

Verification

• pnpm test (181 passing)
• pnpm run typecheck
• pnpm run lint
• pnpm run docs:check
• pnpm run build
• deployed to https://adapters.realmroot.dev
• verified private branch refs and PR listing through the saltbo GitHub Context

Review environment

Use the production Adapter with a GitHub Context that grants repository contents and pull-request permissions. Read a private branch ref and list pull requests through realmroot exec github.

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_{🤖 Created by Jarvis via Realmroot}