feat(auth): add auto-generation of oauth credentials

Implement functionality to create the oauth_creds.json file from
environment variables (ACCESS_TOKEN, REFRESH_TOKEN, EXPIRY_DATE)
if the file is missing. Also update documentation, docker-compose,
and build scripts to support this new feature.

.env.example

@@ -1,3 +1,10 @@
 PORT=11434
 VERBOSE=false
-API_KEY=MY0P3NA1K3Y
+API_KEY=MY0P3NA1K3Y
+ACCESS_TOKEN=MYACC3SS_T0K3N
+REFRESH_TOKEN=MYR3FR3SH_T0K3N
+EXPIRY_DATE=1234567890
+# Docker
+DOCKER_REGISTRY=
+DOCKER_REGISTRY_USER=
+DOCKER_HUB_USER=