Add spec compliance improvements: seed switch alert, calendar emojis, period indicator, IP logging

- NutritionPanel: Display seed switch alert on day 15 per dashboard spec
- MonthView: Add phase emojis to legend (🩸🌱🌸🌙🌑) per calendar spec
- DayCell: Show period indicator (🩸) for days 1-3 per calendar spec
- Auth middleware: Log client IP from x-forwarded-for/x-real-ip per observability spec
- Updated NutritionGuidance type to include seedSwitchAlert field
- /api/today now returns seedSwitchAlert in nutrition response

Test coverage: 1005 tests (15 new tests added)
- nutrition-panel.test.tsx: +4 tests
- month-view.test.tsx: +1 test
- day-cell.test.tsx: +5 tests
- auth-middleware.test.ts: +3 tests
- today/route.test.ts: +2 tests

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/dashboard/nutrition-panel.tsx

@@ -10,6 +10,11 @@ export function NutritionPanel({ nutrition }: NutritionPanelProps) {
   return (
     <div className="rounded-lg border p-4">
       <h3 className="font-semibold mb-4">NUTRITION TODAY</h3>
+      {nutrition.seedSwitchAlert && (
+        <div className="mb-3 p-2 rounded bg-amber-100 dark:bg-amber-900 text-sm font-medium">
+          {nutrition.seedSwitchAlert}
+        </div>
+      )}
       <ul className="space-y-2 text-sm">
         <li>🌱 {nutrition.seeds}</li>
         <li>🍽️ Carbs: {nutrition.carbRange}</li>