fix: case-insensitive MCP server name lookup

[Copilot]

LLMs frequently capitalize server names (e.g. OpenRouter) that are stored lowercase in config (e.g. openrouter), causing spurious "MCP server is not connected" errors and wasted LLM iterations.

Changes

• McpBridgeService — initialize _clients, _serverConfigs, and _serverTools with StringComparer.OrdinalIgnoreCase so all bridge-side lookups are case-insensitive regardless of call source
• McpManagementExecutor — extract TryGetServerName helper that normalizes server_name to lowercase; replaces the inline TryGetString call in mcp_get_service_details, mcp_invoke_tool, and mcp_unregister_server

private static bool TryGetServerName(Dictionary<string, object?> args, out string serverName)
{
    if (!TryGetString(args, "server_name", out serverName))
        return false;
    serverName = serverName.ToLowerInvariant();
    return true;
}

The bridge-side fix is the load-bearing one (handles any caller); the executor-side normalization is defense-in-depth ensuring the name is canonicalized before it leaves the agent process.

Original prompt

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This section details on the original issue you should resolve

<issue_title>MCP server name lookup is case-sensitive, causing spurious tool failures</issue_title>
<issue_description>## Problem

When the agent calls mcp_get_service_details or mcp_invoke_tool, the server name lookup is case-sensitive. mcp_list_services returns server names in lowercase (e.g. openrouter), but the LLM frequently passes a capitalized variant (e.g. OpenRouter), which causes the tool to return Error: MCP server 'OpenRouter' is not connected even when the server is connected.

Observed in logs

Executing tool mcp_invoke_tool(... server_name=OpenRouter, tool_name=list_models ...)
Tool mcp_invoke_tool returned in 6ms: Error: MCP server 'OpenRouter' is not connected

Executing tool mcp_get_service_details(... server_name=OpenRouter)
Tool mcp_get_service_details returned in 7ms: Error: Server 'OpenRouter' is not connected

Executing tool mcp_get_service_details(... server_name=openrouter)   ← lowercase works
Tool mcp_get_service_details returned in 6ms: [...]

The agent wasted 2 extra LLM iterations (and context) before discovering the correct casing.

Fix

Normalize server_name to lowercase (or do a case-insensitive lookup) before resolving the MCP server in mcp_get_service_details, mcp_invoke_tool, mcp_unregister_server, and any other tool that accepts a server name parameter.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes MCP server name lookup is case-sensitive, causing spurious tool failures #60

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