Lets `maestro-registry` run in container deployments (e.g. Dokploy)
without mounting a writable config volume.
- `MAESTRO_TOKEN`: when set, bypasses `registry.toml` entirely (no
read, no write). The container needs no persistent volume just to
seed the shared secret — pass it as a platform secret instead.
- `MAESTRO_REGISTRY_BIND_ADDR`: overrides the file's `bind_addr`.
Lets the container bind `0.0.0.0:$PORT` without rewriting TOML.
- New `load_config(path, env_token, env_bind_addr)` in `token.rs`
centralises the env > file > default precedence. Takes explicit
`Option`s so tests don't touch process-global env.
- `TokenError::InvalidBindAddr` carries the raw input + parse error
so misconfigured deploys log a useful diagnostic.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>