chore(cleanup): drop two dead re-exports before the knip gate flip

W1-KNIP's reconcile callouts identified two re-exports that no caller
ever consumed:

- `src/lib/tz/resolver.ts:51` re-exported `listSupportedTimezones` from
  `./format`, but both call-sites (`components/settings/timezone-picker.tsx`
  and `components/admin/general-settings-section.tsx`) import directly
  from `@/lib/tz/format`.
- `src/components/medications/glp1-medication-card.tsx:595-596`
  re-exported `describeInjectionSite` "so the parent doesn't need to
  import it", but every real consumer (`therapy-timeline.tsx`,
  `injection-site-picker.tsx`, the unit test) imports the source from
  `@/lib/medications/injection-sites` directly.

Drops both re-exports and the now-orphaned `describeInjectionSite`
import in `glp1-medication-card.tsx`. Clears the last knip findings so
the gate flip in the next commit lands clean.

src/components/medications/glp1-medication-card.tsx

@@ -38,7 +38,6 @@ import { formatDateTime, formatTime } from "@/lib/format";
 import { formatTimeWindowRange } from "@/lib/time-window-format";
 import { getMedicationCategoryLabel } from "@/lib/medications/category-label";
 import {
-  describeInjectionSite,
   nextInjectionSite,
   type InjectionSiteKey,
 } from "@/lib/medications/injection-sites";
@@ -591,6 +590,3 @@ function siteSuffix(site: InjectionSiteKey): string {
     .map((part) => part.charAt(0).toUpperCase() + part.slice(1))
     .join("");
 }
-
-/** Re-export so the parent doesn't need to import describeInjectionSite. */
-export { describeInjectionSite };

src/lib/tz/resolver.ts

@@ -48,7 +48,6 @@ export {
   DEFAULT_TIMEZONE,
   isValidTimezone,
   isNearUtc,
-  listSupportedTimezones,
   detectBrowserTimezone,
   formatInUserTz,
   userDayKey,