feat: add Arknights: Endfield, and stop passing off requirements as summaries

Endfield was previously written off as undatable. That was wrong: a first
pass only inspected its Duration rows (all "Permanently Available") and its
year-less version grid, and missed an "Event | Schedule & Summary" table
whose cells read "Period: 08/09/26 - 08/30/26 During the event...". Two real
events, with a year.

Adds MM/DD/YY range parsing for that shape. Month-first ordering is not
assumed lightly — Endfield's own version grid reads 01/22, 04/17, 07/16 for
versions 1.0, 1.2 and 1.4, chronological only if the month comes first.

Also stops presenting unlock conditions as descriptions. Several templates
put "Reach Union Level 8" where a blurb would go; filling the summary slot
with text that never says what the event is is worse than leaving it empty.
Wuthering Waves correctly drops to zero summaries as a result.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

CLAUDE.md

@@ -99,8 +99,9 @@ These come from how gacha games actually schedule things, and they cause most bu
 - **Game8 has no single template.** Three shapes are known so far, and a page may mix them:
   1. Label/value detail tables (`Event Start` / `Event End`) — Genshin.
   2. Column tables (`Event | Duration | Event Details | Rewards`) — NTE.
-  3. Image-grid schedules with a bare `MM/DD` and no end — Arknights: Endfield. **Unsupportable**;
-     yields nothing by design.
+  3. Image-grid schedules with a bare `MM/DD` and no end — unsupportable, yields nothing by design.
+  4. Combined cells that fold label, range and blurb together
+     (`Period: 08/09/26 - 08/30/26 During the event...`) — Arknights: Endfield.
   Before assuming a new Game8 page will work, dump its structure and check which shape it uses.
 - **Silent drops are the dangerous failure.** A date format the parser does not recognise makes
   events vanish with no error. Abbreviated months (`Apr. 29 - May 13, 2026`) are supported for