Fix spec compliance gaps in email and dashboard

- Email subject now follows spec format: PhaseFlow: [STATUS] - Day [cycleDay] ([phase])
- Daily email includes seed switch alert on day 15 (using getSeedSwitchAlert)
- Data panel HRV status now color-coded: green=Balanced, red=Unbalanced, gray=Unknown
- Data panel shows progress bar for week intensity vs phase limit with color thresholds

Adds 13 new tests (990 total).

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

src/lib/email.ts

@@ -4,6 +4,7 @@ import { Resend } from "resend";
 
 import { logger } from "@/lib/logger";
 import { emailSentTotal } from "@/lib/metrics";
+import { getSeedSwitchAlert } from "@/lib/nutrition";
 
 const resend = new Resend(process.env.RESEND_API_KEY);
 
@@ -33,7 +34,12 @@ export async function sendDailyEmail(
   data: DailyEmailData,
   userId?: string,
 ): Promise<void> {
-  const subject = `Today's Training: ${data.decision.icon} ${data.decision.status}`;
+  // Subject format per spec: PhaseFlow: [STATUS] - Day [cycleDay] ([phase])
+  const subject = `PhaseFlow: ${data.decision.icon} ${data.decision.status} - Day ${data.cycleDay} (${data.phase})`;
+
+  // Check for seed switch alert on day 15
+  const seedSwitchAlert = getSeedSwitchAlert(data.cycleDay);
+  const seedSwitchSection = seedSwitchAlert ? `\n\n${seedSwitchAlert}` : "";
 
   const body = `Good morning!
 
@@ -52,7 +58,7 @@ ${data.decision.icon} ${data.decision.reason}
 🌱 SEEDS: ${data.seeds}
 
 🍽️ MACROS: ${data.carbRange}
-🥑 KETO: ${data.ketoGuidance}
+🥑 KETO: ${data.ketoGuidance}${seedSwitchSection}
 
 ---
 Auto-generated by PhaseFlow`;