feat(browser): /browser connect — attach browser tools to live Chrome via CDP

Add /browser slash command for connecting browser tools to the user's
live Chrome instance via Chrome DevTools Protocol:

  /browser connect       — connect to Chrome on localhost:9222
  /browser connect ws://host:port  — custom CDP endpoint
  /browser disconnect    — revert to default (headless/Browserbase)
  /browser status        — show current browser mode + connectivity

When connected:
- All browser tools (navigate, snapshot, click, etc.) control the
  user's real Chrome — logged-in sessions, cookies, open tabs
- Platform-specific Chrome launch instructions are shown
- Port connectivity is tested immediately
- A context message is injected so the model knows it's controlling
  a live browser and should be mindful of user's open tabs

Implementation:
- BROWSER_CDP_URL env var drives the backend selection in browser_tool.py
- New _create_cdp_session() creates sessions using the CDP override
- _get_cdp_override() checked before local/Browserbase selection
- Existing agent-browser --cdp flag handles the actual CDP connection

Inspired by OpenClaw's browser profile system.

tests/hermes_cli/test_commands.py

@@ -12,7 +12,7 @@ EXPECTED_COMMANDS = {
     "/personality", "/clear", "/history", "/new", "/reset", "/retry",
     "/undo", "/save", "/config", "/cron", "/skills", "/platforms",
     "/verbose", "/reasoning", "/compress", "/title", "/usage", "/insights", "/paste",
-    "/reload-mcp", "/rollback", "/background", "/skin", "/voice", "/quit",
+    "/reload-mcp", "/rollback", "/background", "/skin", "/voice", "/browser", "/quit",
 }