Add list action to manage_ka and manage_mas MCP tools

[CheeYuTan]

Summary

Adds a list action to both manage_ka and manage_mas MCP tools, enabling users to discover all Knowledge Assistants and Supervisor Agents in their workspace.

Recreated from #273 (which had CI not triggering due to a stale fork reference).

Changes:

File	Change
agent_bricks.py	Add _ka_list() and _mas_list() helpers using list_all_agent_bricks(tile_type=TileType.KA/MAS)
agent_bricks.py	Add list to action dispatch in manage_ka and manage_mas
auth.py, test_sql.py	Fix pre-existing ruff format issues

New usage:

manage_ka(action="list")
# Returns: {"knowledge_assistants": [...], "count": N}

manage_mas(action="list")
# Returns: {"supervisor_agents": [...], "count": N}

Test plan

• ruff check passes
• ruff format --check passes
• _ka_list uses TileType.KA filter, _mas_list uses TileType.MAS
• Both return structured dicts with tile_id, name, description, and count