🐛 Bug-fix PR

Before opening this PR please:

1. make lint - passes ruff, mypy, pylint
2. make test - all unit + integration tests green
3. make coverage - ≥ 90 %
4. make docker docker-run-ssl or make podman podman-run-ssl
5. Update relevant documentation.
6. Tested with sqlite and postgres + redis.
7. Manual regression no longer fails. Ensure the UI and /version work correctly.

📌 Summary

What problem does this PR fix and why?
Addresses part of Issue #212 - This addresses 3 blocker level issues found by Sonar scan.

🔁 Reproduction Steps

1. Set up local sonarqube server, and scan:

make sonar-deps-podman
make sonar-up-podman
make sonar-info
make pysonar-scanne

2. Open web interface for sonarqube
3. Go to "Issues" tab
4. Select "Blocker" severity
5. From main branch shows 18 issues, following these changes show 15 issues.

🐞 Root Cause

1. in mcpgateway/routers/email_auth.py removed unused/unsupported parameter from function call.
2. in mcpgateway/routers/rbac.py removed unused/unsupported parameter from function call.
3. in mcpgateway/services/email_auth_service.py type hint for old_password didn;t allow for None value passed from https://github.com/IBM/mcp-context-forge/blob/main/mcpgateway/routers/email_auth.py#L583

...
# Update password if provided
    if user_request.password:
        await auth_service.change_password(
            email=user_email,
            old_password=None,  # Admin can change without old password
            new_password=user_request.password,
...

💡 Fix Description

Made changes as required to pass Sonarqube scan for target areas.
Confirmed make test doesn't show any breakages.

🧪 Verification

📐 MCP Compliance (if relevant)

• Matches current MCP spec
• No breaking change to MCP clients

✅ Checklist

• Code formatted (make black isort pre-commit)
• No secrets/credentials committed