Upgrade quarkus-mcp-server from 1.13.1 to 2.0

[kornys]

Summary

Upgrade quarkus.mcp.server.version from 1.13.1 to 2.0 (CR1 now, GA when released) in root pom.xml.

This brings MCP Server API 1.0.0 (stable), stateless protocol groundwork, generic type schema fixes, DNS rebinding protection, and stdio cancellation fixes.

Breaking changes (verified non-impacting)

• SSE artifact removal — we already use quarkus-mcp-server-http
• JSON-RPC batching removed — not used, whenBatch() not called
• McpProtocolVersion enum→class — not referenced
• McpRequest.protocolVersion() return type change — not used
• Error code renumbering — no hardcoded error codes
• ToolOutputGuardrail/ToolInputGuardrail null rejection — we use custom CDI guardrails
• OutputSchemaGenerator.generate(Type) — no custom generators
• Metrics config phase change — already have metrics.enabled=true
• Tracing scoped per-server — use @WithSpan directly

Acceptance criteria

• pom.xml:25 version property updated
• mvn compile passes across all modules
• All unit tests pass
• Evaluate removing quarkus.mcp.server.tools.structured-content.compatibility-mode=true (may be unnecessary with 2.0's fixed generic type schema generation)
• CHANGELOG.md updated