chore: bump mcpg to v0.3.16 and firewall to v0.25.50

[lpcox]

Version Bumps

• MCP Gateway: v0.3.16
• Agent Workflow Firewall: v0.25.50

Notable Changes

mcpg v0.3.16

• OTLP endpoint path compliance: appends /v1/traces per OTEL spec so Go and JS exporters share the same base endpoint URL
• Configurable signal path via TracingConfig.SignalPath
• Proper URL parsing for endpoint resolution (handles query params, fragments, trailing slashes)
• gen_ai semantic convention attributes (gen_ai.tool.name, gen_ai.agent.id, gen_ai.conversation.id)

Firewall v0.25.50

• See release notes

Documentation

• API Proxy OTel/Sentry setup guide: https://github.com/github/gh-aw-firewall/blob/main/docs/otel-sentry.md

This doc covers how to configure OTLP export to Sentry from the firewall proxy, including endpoint format, auth headers, and trace context propagation.