fix(audit): v5 审计修复 8 项 — 条件编译、安全加固、冗余清理

- N1: Whiteboard Export 动作标注 demo=true
- N2/N3: Director + A2A 通过 #[cfg(feature)] 条件编译隔离
- N4: viking_adapter 文本匹配降级为 LOW（生产路径走 SqliteStorage）
- N5: 移除冗余 compactor_compact_llm Tauri 命令注册
- M3: hand_approve/hand_cancel 添加 hand_id 验证防跨 Hand 审批
- N7: scheduled_task 文档注释标注 PLANNNED
- 新增 COMPREHENSIVE_AUDIT_V5.md 独立审计报告
- 更新 DEEP_AUDIT_REPORT.md 追加修复记录（累计 32 项）

crates/zclaw-protocols/Cargo.toml

@@ -7,6 +7,11 @@ repository.workspace = true
 rust-version.workspace = true
 description = "ZCLAW protocol support (MCP, A2A)"
 
+[features]
+default = []
+# Enable A2A (Agent-to-Agent) protocol support
+a2a = []
+
 [dependencies]
 zclaw-types = { workspace = true }
 

crates/zclaw-protocols/src/lib.rs

@@ -1,13 +1,18 @@
 //! ZCLAW Protocols
 //!
 //! Protocol support for MCP (Model Context Protocol) and A2A (Agent-to-Agent).
+//!
+//! A2A is gated behind the `a2a` feature flag (reserved for future multi-agent scenarios).
+//! MCP is always available as a framework for tool integration.
 
 mod mcp;
 mod mcp_types;
 mod mcp_transport;
+#[cfg(feature = "a2a")]
 mod a2a;
 
 pub use mcp::*;
 pub use mcp_types::*;
 pub use mcp_transport::*;
+#[cfg(feature = "a2a")]
 pub use a2a::*;