feat(medications): Wirkung tab + Insights efficacy summary

Add the per-medication "Wirkung" tab (hidden for one-shot and no-target meds)
rendering the target series with a start marker, dose-change markers, shaded
pause bands and a faint reference band, an adherence lane, a neutral
before/after-start card with honest empty states, an optional level-shift note,
and a retarget chooser. Weave a compact, read-only efficacy summary into the
Insights medication surface that reads the same DTO and links through to the
tab. All copy is descriptive; add a banned-verdict-verb guard test over the
medications.efficacy namespace across all six locales.

src/lib/query-keys/medications.ts

@@ -138,4 +138,13 @@ export const medicationKeys = {
    */
   medicationApiEndpoint: (medicationId: string) =>
     ["medications", medicationId, "api-endpoint"] as const,
+  /**
+   * v1.28 — per-medication efficacy view ("Wirkung")
+   * (`GET /api/medications/[id]/efficacy`), consumed by the detail page's
+   * Wirkung tab and the Insights medication summary. Rides under the
+   * `["medications", id, …]` prefix so an intake mutation (which moves the
+   * adherence lane) reaches it through `medicationDependentKeys`.
+   */
+  medicationEfficacy: (medicationId: string) =>
+    ["medications", medicationId, "efficacy"] as const,
 };