feat(skills): WASM host 函数真实实现 — zclaw_log/http_fetch/file_read (Phase 4B)

替换 stub 为真实实现:
- zclaw_log: 读取 guest 内存并 log
- zclaw_http_fetch: ureq v3 同步 GET (10s timeout, network_allowed 守卫)
- zclaw_file_read: 沙箱 /workspace 目录读取 (路径校验防逃逸)
添加 ureq v3 workspace 依赖, 25 测试全通过。

Cargo.lock

@@ -5492,6 +5492,7 @@ version = "0.23.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "758025cb5fccfd3bc2fd74708fd4682be41d99e5dff73c377c0646c6012c73a4"
 dependencies = [
+ "log",
  "once_cell",
  "ring",
  "rustls-pki-types",
@@ -7858,6 +7859,35 @@ version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ecb6da28b8a351d773b68d5825ac39017e680750f980f3a1a85cd8dd28a47c1"
 
+[[package]]
+name = "ureq"
+version = "3.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dea7109cdcd5864d4eeb1b58a1648dc9bf520360d7af16ec26d0a9354bafcfc0"
+dependencies = [
+ "base64 0.22.1",
+ "flate2",
+ "log",
+ "percent-encoding",
+ "rustls",
+ "rustls-pki-types",
+ "ureq-proto",
+ "utf8-zero",
+ "webpki-roots",
+]
+
+[[package]]
+name = "ureq-proto"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e994ba84b0bd1b1b0cf92878b7ef898a5c1760108fe7b6010327e274917a808c"
+dependencies = [
+ "base64 0.22.1",
+ "http 1.4.0",
+ "httparse",
+ "log",
+]
+
 [[package]]
 name = "url"
 version = "2.5.8"
@@ -7895,6 +7925,12 @@ version = "0.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09cc8ee72d2a9becf2f2febe0205bbed8fc6615b7cb429ad062dc7b7ddd036a9"
 
+[[package]]
+name = "utf8-zero"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8c0a043c9540bae7c578c88f91dda8bd82e59ae27c21baca69c8b191aaf5a6e"
+
 [[package]]
 name = "utf8_iter"
 version = "1.0.4"
@@ -9723,7 +9759,6 @@ dependencies = [
  "tracing",
  "uuid",
  "zclaw-hands",
- "zclaw-kernel",
  "zclaw-runtime",
  "zclaw-skills",
  "zclaw-types",
@@ -9840,6 +9875,7 @@ dependencies = [
  "thiserror 2.0.18",
  "tokio",
  "tracing",
+ "ureq",
  "uuid",
  "wasmtime",
  "wasmtime-wasi",