Consolidate with lessons from #4372

Pulls in the useful surface area from @vitobotta's parallel PR #4372
and differentiates on the search_lang default and test coverage.

Credit: the tools_config.py integration, extra_snippets idea, and
BRAVE_API_URL override are all adapted from #4372 (@vitobotta).

Changes:
- hermes_cli/tools_config.py: add Brave Search entry so it shows up in
  the `hermes tools` setup wizard alongside the other backends.
- _brave_search: honour BRAVE_API_URL env var (useful for proxies or
  self-hosted gateways); read at call time, not import time.
- _normalize_brave_search_results: merge up to two extra_snippets into
  the description so callers get the richer context Brave provides
  without changing the standard output shape.
- Intentionally do NOT set `search_lang`. Brave auto-detects the query
  language, which is what we want for non-English users — #4372
  hardcoded `search_lang: "en"` and would downgrade French/other-locale
  searches. Added a regression test.
- Docstring explains the search_lang choice and BRAVE_API_URL escape
  hatch.

Tests added (5 more, total 20):
- test_does_not_set_search_lang — regression guard
- test_brave_api_url_override — env-based base URL redirection
- test_extra_snippets_merged_into_description
- test_extra_snippets_used_when_description_empty
- test_no_extra_snippets

All 20 Brave tests pass; 60 existing Tavily/config tests still pass.

hermes_cli/tools_config.py

@@ -235,6 +235,15 @@ TOOL_CATEGORIES = {
                     {"key": "TAVILY_API_KEY", "prompt": "Tavily API key", "url": "https://app.tavily.com/home"},
                 ],
             },
+            {
+                "name": "Brave Search",
+                "badge": "free tier",
+                "tag": "Independent index, privacy-focused — 2000 free queries/mo; search only (extract/crawl need Firecrawl)",
+                "web_backend": "brave",
+                "env_vars": [
+                    {"key": "BRAVE_API_KEY", "prompt": "Brave Search API key", "url": "https://api-dashboard.search.brave.com/"},
+                ],
+            },
             {
                 "name": "Firecrawl Self-Hosted",
                 "badge": "free · self-hosted",