feat(github-agent): add repo and docs context Q&A from connected sources

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Background

The Dosu-like opportunity is repo-context Q&A, but Gittensory should answer contribution-quality questions rather than becoming a generic docs chatbot.

Goal

Add GitHub command answers from connected repo/docs/signal sources, scoped to contribution quality and repo policy.

Current Behavior

Gittensory has strong structured signals, but not a source-cited GitHub Q&A layer.

Desired Behavior

Maintainers and authorized contributors can ask Gittensory contribution-context questions with cited answers.

Implementation Requirements

• Use repo README/docs only when app permissions allow.
• Use issues, PRs, reviews, checks, signal snapshots, focus manifests, and upstream rulesets as sources.
• Cite sources and freshness.
• Require explicit opt-in before indexing private source/docs.
• Do not send source content to optional AI unless explicitly allowed.

Public/Private Output Boundaries

Public GitHub output must never include wallets, hotkeys, payout/reward estimates, raw trust scores, public score estimates, private reviewability, private scoreability context, or farming language. Private API/MCP/control-panel surfaces may show authenticated scoreability, blockers, projections, and evidence, but must not claim guaranteed payout outcomes.

Acceptance Criteria

• Answers cite sources.
• No source indexing for private repos unless explicitly allowed.
• No source content sent to optional AI without opt-in.
• Tests cover permission boundaries and stale sources.

Testing Requirements

• npm run test:ci must pass.
• Global coverage must remain at or above 97% for lines, statements, functions, and branches.
• Aim for 98%+ branch coverage locally.
• Add tests for every new branch, fallback path, sanitizer rule, and regression.
• Add invariant/property-style tests when behavior depends on sorting, gating, scoring, source-upload safety, public/private boundaries, or telemetry privacy.
• MCP/local tooling must prove source contents are not uploaded when local metadata is involved.
• Public GitHub output must be tested against forbidden language: wallet, hotkey, raw trust score, payout, reward estimate, farming, private reviewability, and public score estimate.