Replace each folder's shared .env.example with one example per compose
file, named after it (docker-compose.<name>.yml takes
.env.<name>.example), as DriverVault does. Each lists only the settings
its compose file uses, names the required ones in its header, and the
prod examples start from a public server name. Every variable a compose
file substitutes is defined in its example.
The compose headers point at their own example. The SeaweedFS files now
fix WARP_PB_S3_REGION at us-east-1 instead of reading it from .env,
since SeaweedFS ignores the region.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>