feat: DeerFlow 2.0 core capabilities — Phase 1.0 + 1.1

Phase 1.0 — Butler Mode UI:
- Hide "自动化" and "技能市场" entries from sidebar navigation
- Remove AutomationPanel and SkillMarket view rendering from App.tsx
- Simplify MainViewType to only 'chat'
- Main interface is now: chat + conversation list + detail panel only

Phase 1.1 — Mode Differentiation:
- Add subagent_enabled field to ChatModeConfig (Rust), StreamChatRequest (Tauri),
  gateway-client, kernel-client, saas-relay-client, and streamStore
- TaskTool is now only registered when subagent_enabled=true (Ultra mode)
- System prompt includes sub-agent delegation instructions only in Ultra mode
- Frontend transmits subagent_enabled from ChatMode config through the full stack

This connects the 4-tier mode selector (Flash/Thinking/Pro/Ultra) to actual
backend behavioral differences — Ultra mode now truly enables sub-agent delegation.

crates/zclaw-kernel/src/kernel/mod.rs

@@ -162,18 +162,22 @@ impl Kernel {
         })
     }
 
-    /// Create a tool registry with built-in tools
-    pub(crate) fn create_tool_registry(&self) -> ToolRegistry {
+    /// Create a tool registry with built-in tools.
+    /// When `subagent_enabled` is false, TaskTool is excluded to prevent
+    /// the LLM from attempting sub-agent delegation in non-Ultra modes.
+    pub(crate) fn create_tool_registry(&self, subagent_enabled: bool) -> ToolRegistry {
         let mut tools = ToolRegistry::new();
         zclaw_runtime::tool::builtin::register_builtin_tools(&mut tools);
 
-        // Register TaskTool with driver and memory for sub-agent delegation
-        let task_tool = zclaw_runtime::tool::builtin::TaskTool::new(
-            self.driver.clone(),
-            self.memory.clone(),
-            self.config.model(),
-        );
-        tools.register(Box::new(task_tool));
+        // Register TaskTool only when sub-agent mode is enabled (Ultra mode)
+        if subagent_enabled {
+            let task_tool = zclaw_runtime::tool::builtin::TaskTool::new(
+                self.driver.clone(),
+                self.memory.clone(),
+                self.config.model(),
+            );
+            tools.register(Box::new(task_tool));
+        }
 
         tools
     }