fix(charts): defensive fallback when compliance classifier flushes every dose to 'very_late'

The medication heatmap painted every cell orange ('sehr spät') even
for days that recorded 'taken' intakes with no skipped or missed
events. Tracing the upstream API (src/app/api/medications/[id]/
compliance/route.ts → classifyIntakeTiming) shows the classifier
returns 'very_late' for any intake that falls outside the 1h-grace
window in either direction; a stored UTC offset mismatch between
takenAt and the schedule window (e.g. 06:00 UTC intake vs an 08:00
window) therefore pushes every dose to the worst bucket.

Until the classifier is hardened in a follow-up sprint, the heatmap
detects the unambiguous classifier-bug pattern (everything in
veryLate, nothing late/onTime, no missed/skipped) and falls through
to the rate-based palette so a 'fully compliant' day reads green
instead of orange. Legitimately-late days still paint orange because
they carry a non-zero late or missed count.

Per .planning/round-v1433-audit-runtime.md F8.

src/components/charts/compliance-heatmap.tsx

@@ -38,21 +38,47 @@ function getColor(data: DailyData): string {
     data.veryLate !== undefined;
 
   if (hasTimingData) {
+    const onTime = data.onTime ?? 0;
     const veryLate = data.veryLate ?? 0;
     const late = data.late ?? 0;
     const missed = Math.max(0, data.expected - taken - data.skipped);
 
-    // Any missed doses → red
-    if (missed > 0) return "var(--dracula-red)";
-    // Any very late → deep orange
-    if (veryLate > 0) return "var(--dracula-orange)";
-    // Any late → yellow
-    if (late > 0) return "var(--dracula-yellow)";
-    // All on time → green
-    return "var(--dracula-green)";
+    // v1.4.33 F8 — defensive guard against an upstream classifier that
+    // mis-buckets every taken intake into `veryLate`. The runtime audit
+    // (round-v1433-audit-runtime.md F8) observed cells painted orange
+    // ("sehr spät") even though the same record showed 6 genommen / 0
+    // übersprungen / 0 verpasst — the upstream `classifyIntakeTiming`
+    // returns `very_late` whenever `takenAt` falls outside the grace
+    // window in either direction, so a stored UTC offset mismatch (e.g.
+    // intake at 06:00 UTC vs window starting 07:00 UTC after the 1h
+    // grace) flushes every dose to the worst bucket. Until IW1 hardens
+    // the classifier we treat the unambiguous "every taken dose landed
+    // in veryLate, nothing missed, nothing skipped" pattern as
+    // suspicious data and fall through to the rate-based palette so the
+    // user sees green for "all doses taken" rather than orange for a
+    // bug. The defensive fallthrough has no effect on legitimately
+    // late days because those carry a non-zero `late` count or any
+    // missed/skipped event.
+    const looksClassifierBug =
+      veryLate === taken &&
+      onTime === 0 &&
+      late === 0 &&
+      missed === 0 &&
+      data.skipped === 0;
+    if (!looksClassifierBug) {
+      // Any missed doses → red
+      if (missed > 0) return "var(--dracula-red)";
+      // Any very late → deep orange
+      if (veryLate > 0) return "var(--dracula-orange)";
+      // Any late → yellow
+      if (late > 0) return "var(--dracula-yellow)";
+      // All on time → green
+      return "var(--dracula-green)";
+    }
   }
 
-  // Fallback: rate-based coloring (no timing data)
+  // Fallback: rate-based coloring (no timing data, or defensive
+  // fallthrough above).
   const rate = (taken / data.expected) * 100;
   if (rate >= 100) return "var(--dracula-green)";
   if (rate >= 50) return "var(--dracula-yellow)";