Usage-limit grace-window messaging made remote-configurable, plus a new wrap-up reminder

What

• The pinned "Usage limit reached" notification shown during a grace window now pulls its headline text from a schema-validated remote config (with running/stopped/credits_on keys) instead of hardcoded strings, changes "resets ..." to "limit resets ...", and adds a clickable link to clau.de/wrap-up.
• This override is controlled by gate tengu_lantern_sconce_copy; if it parses to a valid non-empty value, it replaces the hardcoded messages ("Usage limit reached · wrapping up", "Usage limit reached", "Usage limit reached · brief included wrap-up, then usage credits"), and the parsed value is recorded on the flags diagnostic object.
• A separate new subsystem can inject a system reminder telling Claude to wrap up work ("finish or checkpoint; don't start subagents or long work") when the session is in a usage-limit grace window. Its message text and mode ("wrap-up" vs "next-steps" vs custom) are configurable, and it's off by default, controlled by gate tengu_lantern_wick_braid.

Why

These changes let Claude Code adjust usage-limit messaging without shipping a new release, and give it a way to actively encourage wrapping up work before a usage-limit grace period ends, rather than just showing a static warning.