fix(game8): decide a column table's header by what it produces

Game8's banner pages lay two schedules side by side inside one <table> under a
spanning label row: "Standard Banners | Banner | Rating | Availability | Paid
Banners | ...". That row is not merely unhelpful, it is plausible — it contains
both column words, so it resolves and puts the range at index 3, which no
three-cell data row has. Every row then fails to date and the table yields
nothing at all, with no error anywhere. So readColumnTable now falls back to
row 1, and only when row 0 produced nothing, which is what keeps every page
that parses today parsing identically.

Those pages also schedule banners rather than events and head their sections
accordingly, so the vocabulary learns "List of All Banners", "All Current
Banners" and — the one that matters — "Previous Banners", whose rows are dated
identically to the live ones directly above them.

This parser serves nine sources, so the widening was measured rather than
trusted: every pinned fixture and every live snapshot was parsed before and
after, and no existing source's output changed by a single event.

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

AGENTS.md

@@ -119,7 +119,7 @@ src/client/       React app, service worker, manifest
                   theme.ts — dark or light, and what a game hue reads as on each
 scripts/          build-feed.ts, build-static.ts, parse-fixture.ts (offline), refresh-sources.ts (fetches)
 serve.ts          static server + /api/health
-test/             670 tests
+test/             674 tests
 fixtures/<game>/  raw HTML + .expected.json per source — pinned, kept forever
 snapshots/        current page per source, rewritten by refresh — see its README
 ```
@@ -172,13 +172,27 @@ These come from how gacha games actually schedule things, and they cause most bu
 - **A source may publish more than one region's schedule.** Arknights' wiki lists CN and Global on
   every row, five months apart. Publish the one our readers are on and skip the row that lacks it —
   a CN date on a Global calendar is a confidently wrong date, not a near miss.
-- **Game8 has no single template.** Seven shapes are known and a page may mix them: label/value
+- **Game8 has no single template.** Eight shapes are known and a page may mix them: label/value
   detail tables, column tables, image-grid schedules (unsupportable), combined label+range+blurb
-  cells, rowspan Start/End pairs, labelled `Start: … End: …` cells, and `<hr>`-separated date pairs.
+  cells, rowspan Start/End pairs, labelled `Start: … End: …` cells, `<hr>`-separated date pairs, and
+  two schedules laid side by side in one `<table>` under a spanning label row.
   Full table in `docs/INGESTION.md`. Before assuming a new
   Game8 page will work, dump its structure and check **every** table — Endfield was written off as
   undatable on a pass that only inspected its `Duration` rows, and its real events were further
   down the page.
+- **The header row is the row that dates rows, not the first one.** Game8's banner pages put the
+  Standard and Paid schedules side by side inside one `<table>` and label the pair
+  `Standard Banners | Banner | Rating | Availability | Paid Banners | …`. That row is not merely
+  unhelpful, it is *plausible* — it contains both column words, so it resolves and puts the range at
+  an index no data row has, and the whole table yields nothing with no error anywhere. So
+  `readColumnTable` falls back to row 1 **only when row 0 produced nothing**, which is what keeps
+  every page that parses today parsing identically. Verified rather than assumed: the change was
+  diffed across all pinned fixtures and every live snapshot, and moved no existing event.
+- **Some Game8 wikis schedule banners, not events**, and head their sections accordingly —
+  `List of All Banners`, `All Current Banners`, and a `Previous Banners` back catalogue that
+  `previous events` does not match. All three are in the section vocabulary now. The finished rows
+  sit directly below the live ones and are dated identically, so that exclusion is the only thing
+  between the calendar and a year of expired banners.
 - **Check what fences a section off.** Inclusion is decided by headings, and the level varies: Persona
   5 hides fifty finished events behind nothing but an `<h4>Finished Events</h4>` in a collapsed
   accordion, while Genshin uses `h4` for sub-headings *inside* one event. So `h4` gates sections but