* Resolve secrets from file topology where file name is key and trimmed
file contents are value, compatible with Docker Secrets tmpfs mounting.
* Support [@Key@] token pattern inside Environment Variable strings,
allowing verbose connection strings to live outside declared secrets.
* SecretsPath configurable via environment variable or appSettings,
falling back to working directory for local development convenience.
* Secrets processing occurs at startup before logging, with diagnostics
written to STDOUT.
* Tokenisation extracted into standalone library and included in Dockerfile
* Documentation added covering token pattern and Docker Secrets compatibility.
richard-churchman
5e2195e58d