fix(medications): widen the medication-effect intervals to a week of lag

The automatic Newey-West rule gives a lag of 3 on 30 to 270 daily
values, which leaves most of a physiological series' carry-over out of
the intervals. The lag is now at least 7. Reference values are
recomputed with statsmodels at the new default, and the lag-3 values
stay pinned with an explicit lag. A fit whose residual autocorrelation
exceeds 0.5 is flagged, and the card, the clinician view and the PDF
say the ranges may still be too narrow.

src/components/clinician/activity-effect-sections.tsx

@@ -167,6 +167,11 @@ export function MedicationEffectSection({
                     e.days.excludedLowAdherence + e.days.excludedNotTaking,
                 })}
               </p>
+              {e.fit?.autocorrelationCaveat ? (
+                <p className="text-muted-foreground text-xs">
+                  {t("medications.efficacy.segmented.autocorrelation")}
+                </p>
+              ) : null}
               {e.confounders.map((c) => (
                 <p
                   key={`${c.medicationName}:${c.event}:${c.date}`}

src/components/medications/detail/efficacy/__tests__/change-at-start-summary.test.tsx

@@ -37,7 +37,8 @@ const present: EfficacySegmented = {
     df: 146,
     rSquared: 0.6,
     residualAutocorrelation: 0.3,
-    hacLag: 4,
+    hacLag: 7,
+    autocorrelationCaveat: false,
   },
   confounders: [
     { medicationName: "Example B", event: "started", date: "2026-02-10" },
@@ -70,6 +71,20 @@ describe("ChangeAtStartSummary", () => {
     expect(html).toContain("describes the starting dose");
     expect(html).toContain("Example B started on");
     expect(html).not.toMatch(/work(s|ing)|effective|successful/i);
+    expect(html).not.toContain("medication-wirkung-autocorrelation");
+  });
+
+  it("warns when the daily values carry over strongly", () => {
+    const html = render({
+      ...present,
+      fit: {
+        ...present.fit!,
+        residualAutocorrelation: 0.7,
+        autocorrelationCaveat: true,
+      },
+    });
+    expect(html).toContain("medication-wirkung-autocorrelation");
+    expect(html).toContain("even these ranges may be too narrow");
   });
 
   it("names the missing floor instead of a number", () => {

src/components/medications/detail/efficacy/change-at-start-summary.tsx

@@ -125,6 +125,14 @@ export function ChangeAtStartSummary({
           {t("medications.efficacy.segmented.notTracked")}
         </p>
       ) : null}
+      {segmented.fit?.autocorrelationCaveat ? (
+        <p
+          className="text-muted-foreground text-xs"
+          data-slot="medication-wirkung-autocorrelation"
+        >
+          {t("medications.efficacy.segmented.autocorrelation")}
+        </p>
+      ) : null}
       {segmented.window.endReason === "dose_change" ? (
         <p className="text-muted-foreground text-xs">
           {t("medications.efficacy.segmented.endDoseChange")}