fix(labs): surface truncation hint, drop dead code, document module gate

Add a 'showing latest N of M' hint to the lab list and biomarker detail
when the 500-row cap truncates. Drop the inaccurate amend comment from the
edit history, justify the inline-SVG vs Recharts sparkline split, remove
the unused BiomarkerPanelKey export, and document the deliberate UX-only
(non-server) module gate on the labs + biomarkers routes. New labs i18n
keys added across all six locales.

src/lib/labs/biomarker-catalog.ts

@@ -83,5 +83,3 @@ export const BIOMARKER_PANELS = [
   "electrolytes",
   "bloodCount",
 ] as const;
-
-export type BiomarkerPanelKey = (typeof BIOMARKER_PANELS)[number];