feat(commands): let a PR's own author use chat when rate limiting is active

[JSONbored]

Summary

• Widens @gittensory chat's default authorization from maintainer/collaborator-only to also include pr_author -- scoped to a PR's own author asking about their own PR, never an arbitrary commenter on someone else's.
• The grant is conditional on commandRateLimitPolicy being "hold" for the repo, enforced in evaluateCommandAuthorization (not just by operator convention): a pr_author match on chat only counts as authorized when rate limiting is actually active, so a deployment that hasn't turned on rate limiting stays exactly as conservative as today no matter what chat's configured roles say. This mirrors the existing chatQa/intentRouting OpenAPI field docs, which already document commandRateLimitPolicy: hold as a co-requisite -- this PR is the same pattern applied to authorization, not a new one.
• The existing per-actor rate limiter (maybeThrottleGittensoryCommand) already fits this: keyed by (actor, command, repo#PR), not a shared bucket, and already applies the tighter AI-cost ceiling to chat.
• Fixes normalizeCommandRoleList's clamp so a maintainer's .gittensory.yml restatement of chat's own default (now including pr_author) isn't silently mangled, while every other maintainer-only command (generate-tests, pause, etc.) is completely unaffected -- pr_author still cannot be added to them via override.
• Mirrors the change into packages/gittensory-engine/src/settings/command-authorization.ts to keep test:engine-parity green.

Closes #5084

Test plan

• npm run typecheck
• Full unsharded npm run test:coverage (14366 passed, 0 failed; zero uncovered lines/branches in every touched file)
• npm run command-reference:check / npm run docs:drift-check
• New unit tests: the compound rate-limit gate (off/unset/hold, confirmed-miner-as-pr_author, non-author denial), the clamp fix (restating chat's own default survives; every other maintainer-only command is still clamped), the isAuthorizedCommandActor pass-through
• New end-to-end tests in queue-5.test.ts: a real contributor (no maintainer/collaborator role) reaches chat on their own PR when commandRateLimitPolicy: hold is set, and is silently denied (matching every other unauthorized command) when it isn't

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	gittensory-ui	0dd36ee	Commit Preview URL Branch Preview URL	Jul 11 2026, 02:08 PM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.20%. Comparing base (0800f23) to head (0dd36ee).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5087   +/-   ##
=======================================
  Coverage   94.20%   94.20%           
=======================================
  Files         470      470           
  Lines       39722    39732   +10     
  Branches    14493    14497    +4     
=======================================
+ Hits        37421    37431   +10     
  Misses       1645     1645           
  Partials      656      656           

Flag	Coverage Δ
shard-1	46.42% <57.14%> (+<0.01%)	⬆️
shard-2	33.86% <57.14%> (+0.27%)	⬆️
shard-3	32.27% <28.57%> (+0.93%)	⬆️
shard-4	31.83% <71.42%> (-0.98%)	⬇️
shard-5	33.54% <28.57%> (-0.01%)	⬇️
shard-6	44.89% <50.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...nsory-engine/src/settings/command-authorization.ts	100.00% <100.00%> (ø)
src/github/commands.ts	98.28% <ø> (ø)
src/queue/processors.ts	95.46% <ø> (ø)
src/settings/command-authorization.ts	100.00% <100.00%> (ø)

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