chore: update .env.example with Anthropic key, AI model configuration, and Stripe billing variables

.env.example

@@ -144,18 +144,47 @@ PINTEREST_CLIENT_REDIRECT="${APP_URL}/accounts/pinterest/callback"
 
 # AI Services
 OPENAI_API_KEY=
+ANTHROPIC_API_KEY=
 GEMINI_API_KEY=
 ELEVENLABS_API_KEY=
-ELEVENLABS_DEFAULT_VOICE=EXAVITQu4vr4xnSDxMaL
 
 # AI Provider Selection
 # text:  openai | anthropic | gemini | xai | groq | mistral | deepseek | ...
 # image: openai | gemini | xai
 # audio: openai | elevenlabs
 AI_TEXT_PROVIDER=openai
+AI_TEXT_MODEL=gpt-5.4
 AI_IMAGE_PROVIDER=openai
 AI_AUDIO_PROVIDER=elevenlabs
 
+# ============================================
+# Stripe (Cashier — billing)
+# ============================================
+# Required when SELF_HOSTED=false. Get keys at https://dashboard.stripe.com/apikeys
+STRIPE_KEY=
+STRIPE_SECRET=
+STRIPE_WEBHOOK_SECRET=
+
+# Stripe Plan Price IDs (one per plan × interval). Used by PlanSeeder.
+STRIPE_STARTER_MONTHLY=
+STRIPE_STARTER_YEARLY=
+STRIPE_PLUS_MONTHLY=
+STRIPE_PLUS_YEARLY=
+STRIPE_PRO_MONTHLY=
+STRIPE_PRO_YEARLY=
+STRIPE_MAX_MONTHLY=
+STRIPE_MAX_YEARLY=
+
+# Laravel Nightwatch (production telemetry — disabled by default in dev)
+NIGHTWATCH_ENABLED=false
+NIGHTWATCH_TOKEN=
+
+# Platform feature flags (all default to true; set to false to hide a platform)
+# TIKTOK_ENABLED=true
+# PINTEREST_ENABLED=true
+# MASTODON_ENABLED=true
+# BLUESKY_ENABLED=true
+
 # Media Services
 UNSPLASH_ACCESS_KEY=
 UNSPLASH_SECRET_KEY=