events: whole-series booking + 9 tests

ev/book-series! / ev/cancel-series! apply a booking/cancel to every occurrence
of one event in a window (RSVP the whole weekly class), returning per-
occurrence (occ-key status) results; capacity still enforced per occurrence
(some :booked, some :full), idempotent re-book (:already). ev/series-count,
ev/series-booked. 341/341 green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/events/scoreboard.json

@@ -1,14 +1,14 @@
 {
   "lang": "events",
-  "total_passed": 332,
+  "total_passed": 341,
   "total_failed": 0,
-  "total": 332,
+  "total": 341,
   "suites": [
     {"name":"calendar","passed":51,"failed":0,"total":51},
     {"name":"timezone","passed":17,"failed":0,"total":17},
     {"name":"ical","passed":21,"failed":0,"total":21},
     {"name":"availability","passed":22,"failed":0,"total":22},
-    {"name":"api","passed":32,"failed":0,"total":32},
+    {"name":"api","passed":41,"failed":0,"total":41},
     {"name":"booking","passed":82,"failed":0,"total":82},
     {"name":"booking-notify","passed":11,"failed":0,"total":11},
     {"name":"ticket","passed":31,"failed":0,"total":31},
@@ -17,5 +17,5 @@
     {"name":"federation","passed":29,"failed":0,"total":29},
     {"name":"integration","passed":8,"failed":0,"total":8}
   ],
-  "generated": "2026-06-07T14:40:54+00:00"
+  "generated": "2026-06-07T15:20:08+00:00"
 }