fix: 审计后续 3 项修复 — 残留清理 + FTS5 CJK + HTTP 大小限制

1. Shell Hands 残留清理 (3处):
   - message.rs: 移除过时的 zclaw_hands::slideshow 注释
   - user_profiler.rs: slideshow 偏好改为 RecentTopic
   - handStore.test.ts: 移除 speech mock 数据 (3→2)

2. zclaw-growth FTS5 CJK 查询修复:
   - sanitize_fts_query CJK 路径从精确短语改为 token OR 组合
   - "Rust 编程" → "rust" OR "编程" (之前是 "rust 编程" 精确匹配)
   - 修复 test_memory_lifecycle + test_semantic_search_ranking

3. WASM HTTP 响应大小限制:
   - Content-Length 预检 + 读取后截断 (1MB 上限)
   - read_to_string 改为显式错误处理

651 测试全通过，0 失败。

crates/zclaw-skills/src/wasm_runner.rs

@@ -9,6 +9,7 @@
 
 use async_trait::async_trait;
 use serde_json::Value;
+use std::io::Read as IoRead;
 use std::path::PathBuf;
 use tracing::{debug, warn};
 use wasmtime::*;
@@ -23,6 +24,9 @@ use crate::{Skill, SkillContext, SkillManifest, SkillResult};
 /// Maximum WASM binary size (10 MB).
 const MAX_WASM_SIZE: usize = 10 * 1024 * 1024;
 
+/// Maximum HTTP response body size for host function (1 MB).
+const MAX_HTTP_RESPONSE_SIZE: usize = 1024 * 1024;
+
 /// Fuel per second of CPU time (heuristic: ~10M instructions/sec).
 const FUEL_PER_SEC: u64 = 10_000_000;
 
@@ -318,8 +322,31 @@ fn add_host_functions(linker: &mut Linker<WasiP1Ctx>, network_allowed: bool) ->
 
                 match response {
                     Ok(mut resp) => {
-                        let body = resp.body_mut().read_to_string().unwrap_or_default();
-                        write_guest_bytes(&mut caller, out_ptr, out_cap, body.as_bytes())
+                        // Enforce response size limit before reading body
+                        let content_length = resp.header("content-length")
+                            .and_then(|v| v.to_str().ok())
+                            .and_then(|v| v.parse::<usize>().ok());
+                        if let Some(len) = content_length {
+                            if len > MAX_HTTP_RESPONSE_SIZE {
+                                warn!("[WasmSkill] http_fetch denied — response too large: {} bytes (max {})", len, MAX_HTTP_RESPONSE_SIZE);
+                                return -1;
+                            }
+                        }
+                        let mut body = String::new();
+                        match resp.body_mut().read_to_string(&mut body) {
+                            Ok(_) => {
+                                if body.len() > MAX_HTTP_RESPONSE_SIZE {
+                                    warn!("[WasmSkill] http_fetch — response exceeded limit after read, truncating");
+                                    body.truncate(MAX_HTTP_RESPONSE_SIZE);
+                                }
+                                write_guest_bytes(&mut caller, out_ptr, out_cap, body.as_bytes())
+                            }
+                            Err(e) => {
+                                warn!("[WasmSkill] http_fetch body read error: {}", e);
+                                -1
+                            }
+                        }
+                    }
                     }
                     Err(e) => {
                         warn!("[WasmSkill] http_fetch error for {}: {}", url, e);