feat(routines): say "weekly and monthly" for built-ins

Built-ins now include monthly items, so the strip's question, Settings and Your
own say "weekly and monthly". The per-game tooltip quotes the oldest source
date when a game has several.

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

src/shared/routines.ts

@@ -5,7 +5,7 @@ import { shownFor, type PerGame } from "./perGame.ts";
 import { MeasureSchema, type TaskShape } from "./task.ts";
 
 /**
- * Weekly tasks the app ships for a game — the built-in counterpart of a
+ * Weekly and monthly tasks the app ships for a game — the built-in counterpart of a
  * reader's own `mytask:` (PRD F17).
  *
  * Each is a claim about a game we did not write, so it is held to the bar the