docs(config): add environment variable example

.env.example

@@ -0,0 +1,40 @@
+# Local-only demo mode serves sanitized fixtures and bypasses external services.
+# Keep this false in every deployed environment.
+BUZZ_DEMO_MODE=false
+
+# PostgreSQL
+DATABASE_URL=postgresql://buzz_sheet:[email protected]:5432/buzz_sheet?sslmode=require
+DATABASE_POOL_SIZE=10
+
+# Better Auth + Google OAuth
+BETTER_AUTH_URL=http://localhost:3000
+BETTER_AUTH_SECRET=replace-with-at-least-32-random-bytes
+GOOGLE_CLIENT_ID=replace-with-google-client-id
+GOOGLE_CLIENT_SECRET=replace-with-google-client-secret
+ADMIN_EMAIL=[email protected]
+
+# Redis remote cache, event transport, and outbox worker
+REDIS_URL=rediss://default:[email protected]:6379
+REDIS_CACHE_PREFIX=buzz:next-cache
+REDIS_EVENT_PREFIX=buzz:events
+REDIS_CACHE_MAX_ENTRY_BYTES=5242880
+OUTBOX_BATCH_SIZE=20
+OUTBOX_POLL_MS=1000
+OUTBOX_LEASE_MS=30000
+
+# S3-compatible private media storage
+S3_ENDPOINT=https://s3.example.internal
+S3_REGION=auto
+S3_BUCKET=buzz-sheet-media
+S3_ACCESS_KEY_ID=replace-with-access-key
+S3_SECRET_ACCESS_KEY=replace-with-secret-key
+S3_VIRTUAL_HOSTED_STYLE=false
+
+# Stable across replicas. Generate once and store only in the external secret.
+NEXT_SERVER_ACTIONS_ENCRYPTION_KEY=replace-with-a-stable-32-byte-base64-key
+
+# Set to the immutable image revision for version-skew protection.
+NEXT_DEPLOYMENT_ID=local-development
+
+# Readiness dependency timeout.
+HEALTHCHECK_TIMEOUT_MS=2500

.gitignore

@@ -32,6 +32,7 @@ yarn-error.log*
 
 # env files (can opt-in for committing if needed)
 .env*
+!.env.example
 
 # vercel
 .vercel