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-skills/src/wasm_runner.rs

@@ -1,5 +1,9 @@
 //! WASM skill runner — executes WASM modules in a wasmtime sandbox.
 //!
+//! **Status**: Active module — fully implemented with real wasmtime integration.
+//! Unlike Director/A2A (feature-gated off), this module is compiled by default
+//! but only invoked when a `.wasm` skill is loaded. No feature gate needed.
+//!
 //! Guest modules target `wasm32-wasi` and communicate via stdin/stdout JSON.
 //! Host provides optional functions: `zclaw_log`, `zclaw_http_fetch`, `zclaw_file_read`.