feat: add Brave Search as web search backend

- Add Brave Search as a new web search backend option
- Uses Brave's independent index for privacy-focused search
- Search endpoint: /web/search with X-Subscription-Token auth
- Extract falls back to Firecrawl (Brave doesn't have extract API)
- Added BRAVE_API_KEY environment variable support
- Added Brave Search to tools_config.py provider list
- Free tier: 2,000 queries/month

Backend priority order: firecrawl > parallel > tavily > brave > exa

hermes_cli/tools_config.py

@@ -196,6 +196,14 @@ TOOL_CATEGORIES = {
                     {"key": "FIRECRAWL_API_KEY", "prompt": "Firecrawl API key", "url": "https://firecrawl.dev"},
                 ],
             },
+            {
+                "name": "Brave Search",
+                "tag": "Privacy-focused search with independent index",
+                "web_backend": "brave",
+                "env_vars": [
+                    {"key": "BRAVE_API_KEY", "prompt": "Brave Search API key", "url": "https://brave.com/search/api/"},
+                ],
+            },
             {
                 "name": "Exa",
                 "tag": "AI-native search and contents",