fix(web): add read() via Jina Reader + skill install fallback (#238)

- WebChannel.read(): reads any URL via Jina Reader (r.jina.ai), returns Markdown
- _install_skill(): add fallback from importlib.resources to Path(__file__) for editable installs
- Explicit UTF-8 encoding on all file read/write operations

Inspired by PR #215, implemented correctly (Jina instead of raw requests).

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

agent_reach/channels/web.py

@@ -1,8 +1,11 @@
 # -*- coding: utf-8 -*-
 """Web — any URL via Jina Reader. Always available."""
 
+import urllib.request
 from .base import Channel
 
+_UA = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36"
+
 
 class WebChannel(Channel):
     name = "web"
@@ -15,3 +18,15 @@ class WebChannel(Channel):
 
     def check(self, config=None):
         return "ok", "通过 Jina Reader 读取任意网页（curl https://r.jina.ai/URL）"
+
+    def read(self, url: str) -> str:
+        """通过 Jina Reader 读取网页，返回 Markdown 全文。"""
+        if not url.startswith(("http://", "https://")):
+            url = "https://" + url
+        jina_url = f"https://r.jina.ai/{url}"
+        req = urllib.request.Request(
+            jina_url,
+            headers={"User-Agent": _UA, "Accept": "text/plain"},
+        )
+        with urllib.request.urlopen(req, timeout=30) as resp:
+            return resp.read().decode("utf-8")