feat: complete channel menu install flow + XiaoHongShu channel

Major install flow polish:
- Channels organized by setup difficulty:
  🟢 Zero-config (Web, GitHub, RSS) — works immediately
  🔵 Cookie-based (Twitter, YouTube, Bilibili, XiaoHongShu) — free, ~2min
  🟡 Free API key (Exa Search) — one key, 30 seconds
  🟠 Proxy-based (Reddit, Bilibili on server) — $1/month
- Every channel explains: what it does, what's needed, what you miss without it
- Server vs local affects which channels need proxy

New: XiaoHongShu channel (cookie-based, falls back to Jina Reader)
New configure commands: twitter-cookies, xhs-cookie, youtube-cookies
Each command auto-tests after saving.

agent_eyes/channels/__init__.py

@@ -19,6 +19,7 @@ from .reddit import RedditChannel
 from .rss import RSSChannel
 from .bilibili import BilibiliChannel
 from .exa_search import ExaSearchChannel
+from .xiaohongshu import XiaoHongShuChannel
 
 
 # Channel registry — order matters (first match wins, web is last as fallback)
@@ -28,6 +29,7 @@ ALL_CHANNELS: List[Channel] = [
     YouTubeChannel(),
     RedditChannel(),
     BilibiliChannel(),
+    XiaoHongShuChannel(),
     RSSChannel(),
     ExaSearchChannel(),
     WebChannel(),        # Fallback — handles any URL

agent_eyes/channels/xiaohongshu.py

@@ -0,0 +1,110 @@
+# -*- coding: utf-8 -*-
+"""XiaoHongShu (小红书) — via cookie-based API access.
+
+Backend: XHS web API + cookies
+Swap to: any XHS access method
+"""
+
+import re
+import json
+import requests
+from urllib.parse import urlparse
+from .base import Channel, ReadResult
+
+
+class XiaoHongShuChannel(Channel):
+    name = "xiaohongshu"
+    description = "XiaoHongShu (小红书) notes"
+    backends = ["XHS Web API"]
+    requires_config = ["xhs_cookie"]
+    tier = 2
+
+    def can_handle(self, url: str) -> bool:
+        domain = urlparse(url).netloc.lower()
+        return "xiaohongshu.com" in domain or "xhslink.com" in domain
+
+    async def read(self, url: str, config=None) -> ReadResult:
+        cookie = config.get("xhs_cookie") if config else None
+
+        if not cookie:
+            # Fallback to Jina Reader (works for some public notes)
+            from agent_eyes.channels.web import WebChannel
+            return await WebChannel().read(url, config)
+
+        # Extract note ID from URL
+        note_id = self._extract_note_id(url)
+        if not note_id:
+            from agent_eyes.channels.web import WebChannel
+            return await WebChannel().read(url, config)
+
+        headers = {
+            "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36",
+            "Cookie": cookie,
+            "Referer": "https://www.xiaohongshu.com/",
+        }
+
+        # Fetch note page
+        resp = requests.get(
+            f"https://www.xiaohongshu.com/explore/{note_id}",
+            headers=headers,
+            timeout=15,
+        )
+        resp.raise_for_status()
+        html = resp.text
+
+        # Extract note data from HTML
+        title, content, author = self._parse_html(html)
+
+        return ReadResult(
+            title=title or f"XHS Note {note_id}",
+            content=content or "Could not extract content. Cookie may be expired.",
+            url=url,
+            author=author,
+            platform="xiaohongshu",
+        )
+
+    def _extract_note_id(self, url: str) -> str:
+        """Extract note ID from various XHS URL formats."""
+        # https://www.xiaohongshu.com/explore/xxxxx
+        # https://www.xiaohongshu.com/discovery/item/xxxxx
+        # https://xhslink.com/xxxxx
+        path = urlparse(url).path
+        parts = path.strip("/").split("/")
+        if parts:
+            return parts[-1]
+        return ""
+
+    def _parse_html(self, html: str):
+        """Extract title, content, author from XHS HTML."""
+        title = ""
+        content = ""
+        author = ""
+
+        # Try to find JSON data in page
+        match = re.search(r'window\.__INITIAL_STATE__\s*=\s*({.*?})\s*</script>', html, re.DOTALL)
+        if match:
+            try:
+                # XHS embeds note data in initial state
+                state = json.loads(match.group(1).replace('undefined', 'null'))
+                note_data = state.get("note", {}).get("noteDetailMap", {})
+                if note_data:
+                    first_note = list(note_data.values())[0]
+                    note = first_note.get("note", {})
+                    title = note.get("title", "")
+                    content = note.get("desc", "")
+                    author = note.get("user", {}).get("nickname", "")
+            except (json.JSONDecodeError, KeyError, IndexError):
+                pass
+
+        # Fallback: extract from meta tags
+        if not title:
+            m = re.search(r'<title>(.*?)</title>', html)
+            if m:
+                title = m.group(1)
+
+        if not content:
+            m = re.search(r'<meta name="description" content="(.*?)"', html)
+            if m:
+                content = m.group(1)
+
+        return title, content, author