chore: add support to fetch redis creds from aws secret (#132)

* chore: add support to fetch redis creds from aws secret

* add more checks to the env vars

* fix: surface Redis/Secrets Manager logs, enable TLS, fail loud on connect

The Redis token-store path had three issues that made it silently
non-functional against a TLS-enabled ElastiCache cluster:

- server.py and aws_secrets.py logged via the stdlib root namespace
  (plane_mcp.*), which configure_json_logging() never attaches a handler
  to — so every INFO line ("Using Redis...", "Refreshed secret...") was
  dropped. Switched to fastmcp's get_logger so they nest under the
  configured 'fastmcp' logger.

- The Secrets Manager Redis client was built without TLS. ElastiCache
  mandates in-transit encryption whenever AUTH tokens are used, so the
  connection failed. Added ssl, defaulting on (REDIS_SSL=false to opt out).

- RedisStore connects lazily, so a bad config looked healthy until the
  first OAuth flow. Added an eager PING that raises at startup instead of
  silently degrading.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore: add Redis configuration and route prefix options to .env.test

* refactor: move token storage logic to a dedicated module and update tests for isolated environments

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: akhil-vamshi-konam <konamakhilvamshi@gmail.com>