Add email sent/failed structured logging

Implement email logging per observability spec:
- Add structured logging for email sent (info level) and failed (error level)
- Include userId, type, and recipient fields in log events
- Add userId parameter to email functions (sendDailyEmail, sendPeriodConfirmationEmail, sendTokenExpirationWarning)
- Update cron routes (notifications, garmin-sync) to pass userId

6 new tests added to email.test.ts (now 30 tests total)

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

IMPLEMENTATION_PLAN.md

@@ -4,14 +4,14 @@ This file is maintained by Ralph. Run `./ralph-sandbox.sh plan 3` to generate ta
 
 ## Current State Summary
 
-### Overall Status: 835 tests passing across 44 test files
+### Overall Status: 841 tests passing across 44 test files
 
 ### Library Implementation
 | File | Status | Gap Analysis |
 |------|--------|--------------|
 | `cycle.ts` | **COMPLETE** | 22 tests covering all functions including dynamic phase boundaries for variable cycle lengths |
 | `nutrition.ts` | **COMPLETE** | 17 tests covering getNutritionGuidance, getSeedSwitchAlert, phase-specific carb ranges, keto guidance |
-| `email.ts` | **COMPLETE** | 24 tests covering sendDailyEmail, sendPeriodConfirmationEmail, sendTokenExpirationWarning, email formatting, subject lines |
+| `email.ts` | **COMPLETE** | 30 tests covering sendDailyEmail, sendPeriodConfirmationEmail, sendTokenExpirationWarning, email formatting, subject lines, structured logging |
 | `ics.ts` | **COMPLETE** | 33 tests covering generateIcsFeed (90 days of phase events), ICS format validation, timezone handling, period prediction feedback, CATEGORIES for calendar colors |
 | `encryption.ts` | **COMPLETE** | 14 tests covering AES-256-GCM encrypt/decrypt round-trip, error handling, key validation |
 | `decision-engine.ts` | **COMPLETE** | 8 priority rules + override handling with `getDecisionWithOverrides()`, 24 tests |
@@ -94,7 +94,7 @@ This file is maintained by Ralph. Run `./ralph-sandbox.sh plan 3` to generate ta
 | `src/app/login/page.test.tsx` | **EXISTS** - 32 tests (form rendering, auth flow, error handling, validation, accessibility, rate limiting) |
 | `src/app/page.test.tsx` | **EXISTS** - 28 tests (data fetching, component rendering, override toggles, error handling) |
 | `src/lib/nutrition.test.ts` | **EXISTS** - 17 tests (seed cycling, carb ranges, keto guidance by phase) |
-| `src/lib/email.test.ts` | **EXISTS** - 24 tests (email content, subject lines, formatting, token expiration warnings) |
+| `src/lib/email.test.ts` | **EXISTS** - 30 tests (email content, subject lines, formatting, token expiration warnings, structured logging) |
 | `src/lib/ics.test.ts` | **EXISTS** - 33 tests (ICS format validation, 90-day event generation, timezone handling, period prediction feedback, CATEGORIES for colors) |
 | `src/lib/encryption.test.ts` | **EXISTS** - 14 tests (encrypt/decrypt round-trip, error handling, key validation) |
 | `src/lib/garmin.test.ts` | **EXISTS** - 33 tests (fetchGarminData, fetchHrvStatus, fetchBodyBattery, fetchIntensityMinutes, token expiry, error handling) |
@@ -892,7 +892,7 @@ P4.* UX Polish ────────> After core functionality complete
 - [x] **decision-engine.ts** - Complete with 24 tests (`getTrainingDecision` + `getDecisionWithOverrides`)
 - [x] **pocketbase.ts** - Complete with 9 tests (`createPocketBaseClient`, `isAuthenticated`, `getCurrentUser`, `loadAuthFromCookies`)
 - [x] **nutrition.ts** - Complete with 17 tests (`getNutritionGuidance`, `getSeedSwitchAlert`, phase-specific carb ranges, keto guidance) (P3.2)
-- [x] **email.ts** - Complete with 24 tests (`sendDailyEmail`, `sendPeriodConfirmationEmail`, `sendTokenExpirationWarning`, email formatting) (P3.3, P3.9)
+- [x] **email.ts** - Complete with 30 tests (`sendDailyEmail`, `sendPeriodConfirmationEmail`, `sendTokenExpirationWarning`, email formatting, structured logging for sent/failed events) (P3.3, P3.9)
 - [x] **ics.ts** - Complete with 33 tests (`generateIcsFeed`, ICS format validation, 90-day event generation, period prediction feedback, CATEGORIES for calendar colors) (P3.4, P4.5)
 - [x] **encryption.ts** - Complete with 14 tests (AES-256-GCM encrypt/decrypt, round-trip validation, error handling) (P3.5)
 - [x] **garmin.ts** - Complete with 33 tests (`fetchGarminData`, `fetchHrvStatus`, `fetchBodyBattery`, `fetchIntensityMinutes`, `isTokenExpired`, `daysUntilExpiry`, error handling) (P2.1, P3.6)
@@ -945,7 +945,7 @@ P4.* UX Polish ────────> After core functionality complete
 ### P3: Quality and Testing
 - [x] **P3.1: Decision Engine Tests** - Complete with 24 tests covering all 8 priority rules and override combinations
 - [x] **P3.2: Nutrition Tests** - Complete with 17 tests covering seed cycling, carb ranges, keto guidance by phase
-- [x] **P3.3: Email Tests** - Complete with 24 tests covering daily emails, period confirmation, token expiration warnings
+- [x] **P3.3: Email Tests** - Complete with 30 tests covering daily emails, period confirmation, token expiration warnings, structured logging
 - [x] **P3.4: ICS Tests** - Complete with 28 tests covering ICS format validation, 90-day event generation, timezone handling, period prediction feedback
 - [x] **P3.5: Encryption Tests** - Complete with 14 tests covering AES-256-GCM round-trip, error handling, key validation
 - [x] **P3.6: Garmin Tests** - Complete with 33 tests covering API interactions, token expiry, error handling
@@ -975,7 +975,7 @@ Analysis of all specs vs implementation revealed these gaps:
 |-----|------|--------|-------|
 | Logout functionality | authentication.md | **COMPLETE** | Added POST /api/auth/logout + settings button |
 | Garmin sync structured logging | observability.md | **COMPLETE** | Added sync start/complete/failure logging |
-| Email sent/failed logging | observability.md | **PENDING** | Email events should be logged |
+| Email sent/failed logging | observability.md | **COMPLETE** | Email events now logged (info for success, error for failure) with structured data (userId, emailType, success) |
 | Period history UI | cycle-tracking.md | **PENDING** | UI for viewing/editing past periods |
 | Dashboard color-coded backgrounds | dashboard.md | **PENDING** | Phase-based background colors |
 | Toast notifications | dashboard.md | **PENDING** | Success/error toasts for user actions |