When a port is explicitly specified via CLI flags (e.g., -s3.port=8333),
the config file options should NOT override it. Previously, config file
options would be applied if the flag value differed from default, but
this check wasn't sufficient to prevent override in all cases.
Solution: Check the explicitPortFlags map before applying any config file
port options. If a port was explicitly passed on the CLI, skip applying
the config file option for that port.
This ensures:
- Explicit ports take absolute precedence over config file ports
- Config file ports are only used if port wasn't specified on CLI
- Example: 'weed mini -s3.port=8333' will use 8333, never the config file value