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/app/api/today/route.test.ts

@@ -456,6 +456,40 @@ describe("GET /api/today", () => {
       );
       expect(body.nutrition.carbRange).toBe("75-125g");
     });
+
+    it("returns seed switch alert on day 15", async () => {
+      // Set to cycle day 15 - the seed switch day
+      currentMockUser = createMockUser({
+        lastPeriodDate: new Date("2024-12-27"), // 14 days ago = day 15
+      });
+      currentMockDailyLog = createMockDailyLog({
+        cycleDay: 15,
+        phase: "OVULATION",
+      });
+
+      const response = await GET(mockRequest);
+
+      expect(response.status).toBe(200);
+      const body = await response.json();
+
+      expect(body.nutrition.seedSwitchAlert).toBe(
+        "🌱 SWITCH TODAY! Start Sesame + Sunflower",
+      );
+    });
+
+    it("returns null seed switch alert on other days", async () => {
+      currentMockUser = createMockUser({
+        lastPeriodDate: new Date("2025-01-01"), // cycle day 10
+      });
+      currentMockDailyLog = createMockDailyLog();
+
+      const response = await GET(mockRequest);
+
+      expect(response.status).toBe(200);
+      const body = await response.json();
+
+      expect(body.nutrition.seedSwitchAlert).toBeNull();
+    });
   });
 
   describe("biometrics data", () => {

src/app/api/today/route.ts

@@ -11,7 +11,7 @@ import {
 } from "@/lib/cycle";
 import { getDecisionWithOverrides } from "@/lib/decision-engine";
 import { logger } from "@/lib/logger";
-import { getNutritionGuidance } from "@/lib/nutrition";
+import { getNutritionGuidance, getSeedSwitchAlert } from "@/lib/nutrition";
 import type { DailyData, DailyLog, HrvStatus } from "@/types";
 
 // Default biometrics when no Garmin data is available
@@ -107,8 +107,12 @@ export const GET = withAuth(async (_request, user, pb) => {
     "Decision calculated",
   );
 
-  // Get nutrition guidance
-  const nutrition = getNutritionGuidance(cycleDay);
+  // Get nutrition guidance with seed switch alert
+  const baseNutrition = getNutritionGuidance(cycleDay);
+  const nutrition = {
+    ...baseNutrition,
+    seedSwitchAlert: getSeedSwitchAlert(cycleDay),
+  };
 
   return NextResponse.json({
     decision,