fix(dataplane): forward exact upstream tool names

[lucarlig]

Related PR

Narrow, non-breaking split from #5553. The data-plane support for exact tool-name aliases is already available in contextforge-org/contextforge-data-plane#56.

Summary

• Publish an additive tool_name_aliases mapping from the existing ContextForge-visible tool name to the exact upstream MCP tool name.
• Preserve the current backend identifiers, allowed_tool_names, tool schemas, and Python-facing tool names.
• Forward explicit SDK names unchanged; for example, a tool registered as admin.tools.list is routed upstream as admin.tools.list rather than a reconstructed or slugified value.
• Scope aliases with the same per-user visibility filtering as the tool list.

Compatibility

This is additive and does not change the existing payload fields or naming model. Consumers that support tool_name_aliases use the exact mapping; consumers that ignore unknown fields continue to use the existing payload unchanged.

Type of Change

• Bug fix

Verification

Check	Command	Status
Focused unit tests	.venv/bin/python -m pytest tests/unit/mcpgateway/services/test_dataplane_publisher.py -q	26 passed
Ruff	make ruff TARGET="mcpgateway/services/dataplane_publisher.py tests/unit/mcpgateway/services/test_dataplane_publisher.py"	Passed
Black	make black CHECK=1 TARGET="mcpgateway/services/dataplane_publisher.py tests/unit/mcpgateway/services/test_dataplane_publisher.py"	Passed
Type checks	make ty and make pyrefly on mcpgateway/services/dataplane_publisher.py	Passed
Security lint	make bandit TARGET="mcpgateway/services/dataplane_publisher.py"	Passed
Pylint	make pylint TARGET="mcpgateway/services/dataplane_publisher.py"	10.00/10
Pre-commit	pre-commit on both changed files	Passed

Checklist

• One clear purpose
• Tests included with the behavior they validate
• Code formatted and linted
• No secrets or credentials committed