feat: explore tab, React Query data layer, programs, sync, analytics, testing infrastructure

- Replace browse tab with Supabase-connected explore tab with filters
- Add React Query for data fetching with loading states
- Add 3 structured programs with weekly progression
- Add Supabase anonymous auth sync service
- Add PostHog analytics with screen tracking and events
- Add comprehensive test strategy (Vitest + Maestro E2E)
- Add RevenueCat subscription system with DEV simulation
- Add i18n translations for new screens (EN/FR/DE/ES)
- Add data deletion modal, sync consent modal
- Add assessment screen and program routes
- Add GitHub Actions CI workflow
- Update activity store with sync integration

.maestro/flows/subscription.yaml

@@ -0,0 +1,38 @@
+# Subscription Paywall Test
+# Tests the paywall subscription flow
+# This test requires a fresh install (onboarding not completed)
+
+appId: com.millianlmx.tabatafit
+name: Subscription Paywall
+
+---
+# Navigate through onboarding to paywall (steps 1-5)
+- tapOn: "onboarding-problem-cta"
+- tapOn: "barrier-no-time"
+- tapOn: "onboarding-empathy-continue"
+- tapOn: "onboarding-solution-cta"
+- tapOn: "onboarding-wow-cta"
+
+# Enter name to enable continue
+- tapOn: "name-input"
+- inputText: "Premium User"
+- tapOn: "onboarding-personalization-continue"
+
+# On paywall screen
+- assertVisible: "plan-yearly"
+- assertVisible: "plan-monthly"
+- assertVisible: "subscribe-button"
+- assertVisible: "skip-paywall"
+
+# Test plan selection
+- tapOn: "plan-monthly"
+- assertVisible: "subscribe-button"
+
+# Test restore purchases
+- tapOn: "restore-purchases"
+
+# Skip paywall
+- tapOn: "skip-paywall"
+
+# Verify home screen
+- assertVisible: "program-card-upper-body"