feat(browser): multi-provider cloud browser support + Browser Use integration

Introduce a cloud browser provider abstraction so users can switch
between Local Browser, Browserbase, and Browser Use (or future providers)
via hermes tools / hermes setup.

Cloud browser providers are behind an ABC (tools/browser_providers/base.py)
so adding a new provider is a single-file addition with no changes to
browser_tool.py internals.

Changes:
- tools/browser_providers/ package with ABC, Browserbase extraction,
  and Browser Use provider
- browser_tool.py refactored to use _PROVIDER_REGISTRY + _get_cloud_provider()
  (cached) instead of hardcoded _is_local_mode() / _create_browserbase_session()
- tools_config.py: generic _is_provider_active() / _detect_active_provider_index()
  replace TTS-only logic; Browser Use added as third browser option
- config.py: BROWSER_USE_API_KEY added to OPTIONAL_ENV_VARS + show_config + allowlist
- subprocess pipe hang fix: agent-browser daemon inherits pipe fds,
  communicate() blocks. Replaced with Popen + temp files.

Original PR: #1208
Co-authored-by: ShawnPana <shawnpana@users.noreply.github.com>

tools/browser_providers/browser_use.py

@@ -0,0 +1,107 @@
+"""Browser Use cloud browser provider."""
+
+import logging
+import os
+import uuid
+from typing import Dict
+
+import requests
+
+from tools.browser_providers.base import CloudBrowserProvider
+
+logger = logging.getLogger(__name__)
+
+_BASE_URL = "https://api.browser-use.com/api/v2"
+
+
+class BrowserUseProvider(CloudBrowserProvider):
+    """Browser Use (https://browser-use.com) cloud browser backend."""
+
+    def provider_name(self) -> str:
+        return "Browser Use"
+
+    def is_configured(self) -> bool:
+        return bool(os.environ.get("BROWSER_USE_API_KEY"))
+
+    # ------------------------------------------------------------------
+    # Session lifecycle
+    # ------------------------------------------------------------------
+
+    def _headers(self) -> Dict[str, str]:
+        api_key = os.environ.get("BROWSER_USE_API_KEY")
+        if not api_key:
+            raise ValueError(
+                "BROWSER_USE_API_KEY environment variable is required. "
+                "Get your key at https://browser-use.com"
+            )
+        return {
+            "Content-Type": "application/json",
+            "X-Browser-Use-API-Key": api_key,
+        }
+
+    def create_session(self, task_id: str) -> Dict[str, object]:
+        response = requests.post(
+            f"{_BASE_URL}/browsers",
+            headers=self._headers(),
+            json={},
+            timeout=30,
+        )
+
+        if not response.ok:
+            raise RuntimeError(
+                f"Failed to create Browser Use session: "
+                f"{response.status_code} {response.text}"
+            )
+
+        session_data = response.json()
+        session_name = f"hermes_{task_id}_{uuid.uuid4().hex[:8]}"
+
+        logger.info("Created Browser Use session %s", session_name)
+
+        return {
+            "session_name": session_name,
+            "bb_session_id": session_data["id"],
+            "cdp_url": session_data["cdpUrl"],
+            "features": {"browser_use": True},
+        }
+
+    def close_session(self, session_id: str) -> bool:
+        try:
+            response = requests.patch(
+                f"{_BASE_URL}/browsers/{session_id}",
+                headers=self._headers(),
+                json={"action": "stop"},
+                timeout=10,
+            )
+            if response.status_code in (200, 201, 204):
+                logger.debug("Successfully closed Browser Use session %s", session_id)
+                return True
+            else:
+                logger.warning(
+                    "Failed to close Browser Use session %s: HTTP %s - %s",
+                    session_id,
+                    response.status_code,
+                    response.text[:200],
+                )
+                return False
+        except Exception as e:
+            logger.error("Exception closing Browser Use session %s: %s", session_id, e)
+            return False
+
+    def emergency_cleanup(self, session_id: str) -> None:
+        api_key = os.environ.get("BROWSER_USE_API_KEY")
+        if not api_key:
+            logger.warning("Cannot emergency-cleanup Browser Use session %s — missing credentials", session_id)
+            return
+        try:
+            requests.patch(
+                f"{_BASE_URL}/browsers/{session_id}",
+                headers={
+                    "Content-Type": "application/json",
+                    "X-Browser-Use-API-Key": api_key,
+                },
+                json={"action": "stop"},
+                timeout=5,
+            )
+        except Exception as e:
+            logger.debug("Emergency cleanup failed for Browser Use session %s: %s", session_id, e)