feat: P0 KernelClient功能修复 + P1/P2/P3质量改进

P0 KernelClient 功能断裂修复:
- Skill CUD: registry.rs create/update/delete + serialize_skill_md + kernel proxy
- Workflow CUD: pipeline_commands.rs create/update/delete + serde_yaml依赖
- Agent更新: registry update方法 + AgentConfigUpdated事件 + agent_update命令
- Hand流式事件: HandStart/HandEnd变体替换ToolStart/ToolEnd
- 后端验证: hand_get/hand_run_status/hand_run_list确认实现完整
- Approval闭环: respond_to_approval后台spawn+5分钟超时轮询

P2/P3 质量改进:
- Browser WebDriver: TCP探测ChromeDriver/GeckoDriver/Edge端口替换硬编码true
- api-fallbacks: 移除假技能和16个捏造安全层，替换为真实能力映射
- dead_code清理: 移除5个模块级#![allow(dead_code)]，删除3个真正死方法，
  删除未注册的compactor_compact_llm命令，warnings从8降到3
- 所有变更通过cargo check + tsc --noEmit验证

desktop/src-tauri/src/lib.rs

@@ -1331,6 +1331,7 @@ pub fn run() {
             kernel_commands::agent_list,
             kernel_commands::agent_get,
             kernel_commands::agent_delete,
+            kernel_commands::agent_update,
             kernel_commands::agent_export,
             kernel_commands::agent_import,
             kernel_commands::agent_chat,
@@ -1339,6 +1340,9 @@ pub fn run() {
             kernel_commands::skill_list,
             kernel_commands::skill_refresh,
             kernel_commands::skill_execute,
+            kernel_commands::skill_create,
+            kernel_commands::skill_update,
+            kernel_commands::skill_delete,
             // Hands commands (autonomous capabilities)
             kernel_commands::hand_list,
             kernel_commands::hand_execute,
@@ -1365,6 +1369,9 @@ pub fn run() {
             // Pipeline commands (DSL-based workflows)
             pipeline_commands::pipeline_list,
             pipeline_commands::pipeline_templates,            pipeline_commands::pipeline_get,
+            pipeline_commands::pipeline_create,
+            pipeline_commands::pipeline_update,
+            pipeline_commands::pipeline_delete,
             pipeline_commands::pipeline_run,
             pipeline_commands::pipeline_progress,
             pipeline_commands::pipeline_cancel,