feat(commands): @gittensory pause command — parse + classify + record auto-review-paused state (dispatch scaffold)

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Wire the @gittensory pause PR-comment command that pauses AUTO-REVIEW for this PR only. #1960 hard constraint: pause affects ONLY auto-review, NOT gate enforcement — it must never flip the gate to advisory or bypass the one-shot disposition. The engine already models an execution mode (AgentActionMode paused|dry_run|live, src/settings/agent-execution.ts:16) and a per-repo agent pause. Contributor scope = the parser recognition + classifier + authorization + recording a per-PR auto-review-paused marker (an audit event the sweep/webhook re-review path can read) + tests. The gate-enforcement side and any repository_settings kill-switch mutation stay maintainer-owned; this bounty must include a test proving the gate/disposition is not touched.

Deliverables

• Add maybeProcessPauseCommand: classify → evaluateCommandAuthorization("pause") → record a github_app.autoreview_paused audit event keyed to repo#pr (marker the re-review path can honor)
• Explicitly scope to auto-review: add a code comment + a test asserting no AgentActionMode/gate mutation and no advisory flip
• Reuse the shared preamble/classifier + the gate-override recording shape for skip/denied/completed
• Post a public-safe confirmation comment (sanitizePublicComment) stating auto-review is paused and the gate is unaffected
• Unit tests: authorized pause records the marker, unauthorized→denied, skips, and an assertion that gate disposition state is unchanged (both branches)

References

• src/settings/agent-execution.ts:16 (AgentActionMode)
• src/settings/agent-execution.ts:31 (resolveAgentActionMode)
• src/queue/processors.ts:5977 (handler pattern)
• src/github/commands.ts:1493 (sanitizePublicComment)
• #1960

Part of #1960.

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size: S · held for later release (gittensor:feature once activated)

[linear-code]

JSO-2265