fix(cli): normalize saved platform tool entries

[LeonSGP43]

Summary

• normalize saved platform tool entries to strings before preserving and sorting them
• drop a stale no_mcp sentinel when the new selection explicitly re-enables MCP server entries
• add regressions for the stale sentinel and numeric YAML-name save paths

Testing

• pytest -o addopts='' tests/hermes_cli/test_tools_config.py
• issue repro script from [Bug]: _save_platform_tools preserves stale no_mcp and still crashes on numeric entries #13028

Fixes #13028

[alt-glitch]

Likely duplicate of #13086 — same fix for stale no_mcp sentinel and numeric toolset name normalization (#13028).

[teknium1]

Thanks for the PR, @LeonSGP43! Both fixes here are already on main.

This is an automated hermes-sweeper review.

• String normalization ([str(ts) for ts in existing_toolsets]) landed in hermes_cli/tools_config.py line 802 via commit 9d7b64b5d.
• Stale no_mcp sentinel discard (preserved_entries.discard('no_mcp')) is present at line 814 of the same file, added in the same commit.
• Member @alt-glitch flagged this as a duplicate of fix(cli): clear stale no_mcp and normalize numeric toolset names on save (#13028) #13086, which covers the same two defects from issue [Bug]: _save_platform_tools preserves stale no_mcp and still crashes on numeric entries #13028.

Both fixes are confirmed present in the current main branch. Closing as implemented.