Adjust logging level for frequent / low-level events

[mattt]

Resolves #129

[Copilot]

Pull Request Overview

Lower log level from debug to trace for frequent/low-level events across server, client, and transport layers.

• Replace logger.debug calls with logger.trace for batch, request/response, notification, heartbeat, and SSE events.
• No functional changes; purely adjusts verbosity.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Sources/MCP/Server/Server.swift	Lowered batch, request, and notification logs from debug to trace
Sources/MCP/Client/Client.swift	Changed response, notification, and batch response logs to trace
Sources/MCP/Base/Transports/StdioTransport.swift	Updated message reception logs from debug to trace
Sources/MCP/Base/Transports/NetworkTransport.swift	Adjusted heartbeat and connection logs from debug to trace
Sources/MCP/Base/Transports/HTTPClientTransport.swift	Swapped debug to trace for SSE, JSON, and session ID signaling logs

Comments suppressed due to low confidence (1)

Sources/MCP/Base/Transports/HTTPClientTransport.swift:439

• Indentation for this logger.trace call is inconsistent with the surrounding block; align it with the other logging statements (16 spaces).

logger.trace(