feat: add Stella Sora, from the wiki's front page rather than its banner list

This wiki publishes the same schedule twice and the fuller surface is the worse
one. /wiki/Banner_List has 55 clean rows with full wall clocks and states no
timezone anywhere on the page; the front page's Current Banners module emits
the same instants as real <time datetime="...-07:00"> elements. The two agree
exactly, which is strong evidence the list is UTC and is still only evidence —
so we read the surface that says what it means and pay four live banners
instead of a full history for it. If an editor ever states the zone on
Banner_List, that page becomes the better source immediately.

Two ways this could have failed silently. The template writes its BEM
underscores as &#95;&#95;, so a selector written against the class name a
browser shows matches nothing at all; and banner names are red links to
?action=edit&redlink=1, which Miraheze's robots.txt disallows, so a href
carrying a query is refused and the page URL stands in.

No resetOffsets, and here the source did state an offset: -07:00, which is US
Pacific and therefore shifts twice a year. That is the Fate/Grand Order gap
arriving through a page that looks like it answered the question.

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

docs/PRD.md

@@ -59,7 +59,7 @@ have a source — this table is the launch scope, not a roster to keep in sync.
 
 Adding a game must require no change to `GachaEvent` — only a `GameId` entry, its `games.ts`
 metadata, and a source registration. That is the test of whether the data model is right, and it has
-held: the fourteen games here have cost the event schema nothing. Per-game *metadata* does occasionally
+held: the fifteen games here have cost the event schema nothing. Per-game *metadata* does occasionally
 grow (Reverse: 1999 needed `resetHourLocal` for a 05:00 reset), which is a different file and moves
 no stored key. A game may have several sources; see `docs/INGESTION.md` § Three layers.
 
@@ -90,7 +90,7 @@ default `"game"` — the board every existing reader already has). Merged, the o
 `endingSoonestFirst`, the same comparator behind the list's "Ending soonest" (F2), so the two views
 cannot mean different things by the same words and an unannounced end still sorts behind every dated
 one rather than claiming a place in the queue. Merged there is also no lane heading to say whose
-event a bar is, and hue alone cannot answer that once fourteen games share a stack — so each bar
+event a bar is, and hue alone cannot answer that once fifteen games share a stack — so each bar
 carries its game's short name, with the full name in its tooltip. A bar too narrow for a tag and a
 title both keeps the title: a chopped game name reads as a broken word, and the hue and the tooltip
 still answer it.