feat(kvb-coach): run the short coach at the first prompt of every full hour

hooks/reminder.sh claims the current clock hour with an atomic mkdir under ~/.claude/.coach-hours/, so only the first prompt of the hour across all agents gets the COACH HOUR hint (at most three lines, most urgent area first, then the request); earlier hours are removed. enable-plugins.js registers it next to the kvb-dream reminder. test_coach covers once per hour, silence within the hour and the cleanup; test_dream checks the single registration. Operator order 2026-11-03.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/enable-plugins.js

@@ -15,7 +15,7 @@ const MARKETPLACES = {
   ponytail: { source: { source: "github", repo: "DietrichGebert/ponytail" } },
 };
 const PLUGINS = { "caveman@caveman": true, "ponytail@ponytail": true };
-const REMINDERS = ["kvb-dream"];
+const REMINDERS = ["kvb-dream", "kvb-coach"];
 const RETIRED = [
   "autotune/hooks/reminder.sh",
   "kvb-skills-tune/hooks/reminder.sh",