Telemetry: record tool calls rejected by input schemas

[valentinozegna]

Summary

• instrument the MCP tools/call request boundary so SDK input-schema rejections are observable
• preserve existing handler-level telemetry and exception classes without double-reporting
• classify validation failures as invalid_argument and carry the SDK validation message into error.message
• record the rejected call in local JSONL and OpenTelemetry calls/errors/duration/log/span output
• document that schema-rejected calls are included

Closes #191

Testing

• npm run type-check
• npm run lint
• npm test (995 passed, 5 skipped)
• npm run build
• end-to-end OTLP test verifies one error span, one error log, tool.calls, tool.errors, invalid_argument, and the offending search_path argument
• Bun standalone binary smoke-built with VERSION=1.7.5 and reported v1.7.5