New /limit-reset command and 'Cedar Ember' rate-limit reset option

What

• A new hidden slash command, /limit-reset, lets a Max/Pro user immediately consume an available session-limit reset, with a confirmation dialog and messaging for success, already-used, and unconfirmed cases.
• Internally this is the "cedar_ember" feature: it fetches eligibility and status from a cedar_ember status block, offers a reset when a hard rate limit or an early/anytime limit is hit, and calls a reset_rate_limits server endpoint with program cedar_ember. It tracks separate grants for five_hour, seven_day, seven_day_opus, and seven_day_sonnet limits.
• The rate-limit options menu shown when hitting usage limits gained a second offer type, "cedar-ember", alongside the existing "juniper-tide" offer, described as "Use your reset now ({left} left, until {date})".
• New notification/interrupt kinds cedar-ember and cedar-ember-spent were added to notification-priority and interrupt-suppression handling, and the usage-fetch function gained a third read mode, cedar_ember, hitting /api/oauth/usage?cedar_ember=1&skip_spend=1, feeding two new notice-bar kinds, cedar-ember-offer and cedar-ember-spent.

Why This gives eligible users a self-service way to claim an early reset of their usage limits instead of waiting out the full window, offered both as a direct command and right when a limit is actually hit.