chore: drop the em dashes this release added to prose and test titles

The notification categories' contract description, which lands in the
published API document, and a handful of new code comments and test
titles used em dashes; the house style keeps them out of new prose.

src/__tests__/display-transform-rounding-guard.test.ts

@@ -45,7 +45,7 @@ const REGISTRY = "lib/measurements/display-transform.ts";
 /**
  * The one module allowed to import the unrounded escape hatch. The target
  * adapter needs the unrounded pound edge of a canonical guardrail so it can
- * round it INWARD — rounding to the nearest tenth first can put the pound
+ * round it INWARD: rounding to the nearest tenth first can put the pound
  * edge outside the kilogram window, and the server rejects what converts
  * back from it.
  */