docs(commands): document the @gittensory PR command surface (verbs, roles, auto-review-vs-gate boundary)

[JSONbored]

The #1960 command surface (review/re-review, pause, resume, resolve, help, configuration, explain) needs a single reference doc: each verb, its argument, the default authorization role, and the hard constraint that pause/resume affect ONLY auto-review and NEVER flip the gate to advisory or bypass the one-shot disposition. Ground the doc in the shipped registry (src/github/commands.ts) and the command-authorization defaults so it stays accurate. Docs-only PR (no src changes → no Codecov gate), so keep it tightly scoped.

Deliverables

• Add a docs page (e.g. docs/ or the self-host guide) listing every @gittensory command with: syntax, argument, default allowed roles (from DEFAULT_COMMAND_AUTHORIZATION_POLICY), and effect
• State the hard boundary explicitly: commands never flip the gate to advisory / never bypass the one-shot disposition; pause/resume touch only auto-review
• Document how a maintainer overrides per-command roles via .gittensory.yml commandAuthorization (mirroring the resolved yml>DB>defaults order)
• Link the doc from the command help card and the existing self-host review docs; no secrets/reward/trust values in examples

References

• src/github/commands.ts:48 (command catalog)
• src/settings/command-authorization.ts:3 (default roles)
• src/settings/agent-execution.ts:16 (auto-review modes)
• #1960

Part of #1960.

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size: XS · held for later release (gittensor:bug once activated)

[linear-code]

JSO-2272