refactor(crates): kernel/generation module split + DeerFlow optimizations + middleware + dead code cleanup

- Split zclaw-kernel/kernel.rs (1486 lines) into 9 domain modules
- Split zclaw-kernel/generation.rs (1080 lines) into 3 modules
- Add DeerFlow-inspired middleware: DanglingTool, SubagentLimit, ToolError, ToolOutputGuard
- Add PromptBuilder for structured system prompt assembly
- Add FactStore (zclaw-memory) for persistent fact extraction
- Add task builtin tool for agent task management
- Driver improvements: Anthropic/OpenAI extended thinking, Gemini safety settings
- Replace let _ = with proper log::warn! across SaaS handlers
- Remove unused dependency (url) from zclaw-hands

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

@@ -0,0 +1,79 @@
+//! Skills management methods
+
+use std::sync::Arc;
+use zclaw_types::Result;
+
+use super::Kernel;
+
+impl Kernel {
+    /// Get the skills registry
+    pub fn skills(&self) -> &Arc<zclaw_skills::SkillRegistry> {
+        &self.skills
+    }
+
+    /// List all discovered skills
+    pub async fn list_skills(&self) -> Vec<zclaw_skills::SkillManifest> {
+        self.skills.list().await
+    }
+
+    /// Refresh skills from a directory
+    pub async fn refresh_skills(&self, dir: Option<std::path::PathBuf>) -> Result<()> {
+        if let Some(path) = dir {
+            self.skills.add_skill_dir(path).await?;
+        } else if let Some(ref skills_dir) = self.config.skills_dir {
+            self.skills.add_skill_dir(skills_dir.clone()).await?;
+        }
+        Ok(())
+    }
+
+    /// Get the configured skills directory
+    pub fn skills_dir(&self) -> Option<&std::path::PathBuf> {
+        self.config.skills_dir.as_ref()
+    }
+
+    /// Create a new skill in the skills directory
+    pub async fn create_skill(&self, manifest: zclaw_skills::SkillManifest) -> Result<()> {
+        let skills_dir = self.config.skills_dir.as_ref()
+            .ok_or_else(|| zclaw_types::ZclawError::InvalidInput(
+                "Skills directory not configured".into()
+            ))?;
+        self.skills.create_skill(skills_dir, manifest).await
+    }
+
+    /// Update an existing skill
+    pub async fn update_skill(
+        &self,
+        id: &zclaw_types::SkillId,
+        manifest: zclaw_skills::SkillManifest,
+    ) -> Result<zclaw_skills::SkillManifest> {
+        let skills_dir = self.config.skills_dir.as_ref()
+            .ok_or_else(|| zclaw_types::ZclawError::InvalidInput(
+                "Skills directory not configured".into()
+            ))?;
+        self.skills.update_skill(skills_dir, id, manifest).await
+    }
+
+    /// Delete a skill
+    pub async fn delete_skill(&self, id: &zclaw_types::SkillId) -> Result<()> {
+        let skills_dir = self.config.skills_dir.as_ref()
+            .ok_or_else(|| zclaw_types::ZclawError::InvalidInput(
+                "Skills directory not configured".into()
+            ))?;
+        self.skills.delete_skill(skills_dir, id).await
+    }
+
+    /// Execute a skill with the given ID and input
+    pub async fn execute_skill(
+        &self,
+        id: &str,
+        context: zclaw_skills::SkillContext,
+        input: serde_json::Value,
+    ) -> Result<zclaw_skills::SkillResult> {
+        // Inject LLM completer into context for PromptOnly skills
+        let mut ctx = context;
+        if ctx.llm.is_none() {
+            ctx.llm = Some(self.llm_completer.clone());
+        }
+        self.skills.execute(&zclaw_types::SkillId::new(id), &ctx, input).await
+    }
+}