chore(web): remove web_crawl tool + provider crawl plumbing (#33824)

The web_crawl_tool() function was an orphan — no model schema registered
it, no skill or CLI command called it, and the agent had no way to invoke
it. PR #32608 proposed wiring it up as a model-callable tool; we've
decided not to expose crawl as a separate capability since web_search +
web_extract cover the use cases we want models to have.

Removed:
- tools/web_tools.py: web_crawl_tool() (~230 LOC)
- plugins/web/firecrawl/provider.py: supports_crawl() + crawl()
- plugins/web/tavily/provider.py: supports_crawl() + crawl()
- plugins/web/xai/provider.py: supports_crawl() override
- agent/web_search_provider.py: supports_crawl() + crawl() ABC methods
- agent/web_search_registry.py: get_active_crawl_provider() +
  the 'crawl' branch in _resolve()
- agent/display.py: web_crawl tool-progress rendering
- hermes_cli/config.py: 'web_crawl' from TAVILY_API_KEY.tools
- tools/website_policy.py: stale comment reference
- Tests: removed TestWebCrawlTavily class, the two website-policy
  web_crawl tests, the searxng/ddgs/brave-free crawl-error tests,
  the integration test_web_crawl method, and the
  test_unconfigured_crawl_emits_top_level_error test. Trimmed the
  capability-flag parametrize list and the WebSearchProvider ABC
  conformance tests.
- Docs: trimmed the Crawl column from capability tables in both EN
  and zh-Hans, updated the developer-guide ABC table.

Net: 25 files, +115/-1067.

Closes #33762 (the schema-text bug only existed if #32608 landed).
Supersedes #32608.

hermes_cli/config.py

@@ -2505,10 +2505,10 @@ OPTIONAL_ENV_VARS = {
         "advanced": True,
     },
     "TAVILY_API_KEY": {
-        "description": "Tavily API key for AI-native web search, extract, and crawl",
+        "description": "Tavily API key for AI-native web search and extract",
         "prompt": "Tavily API key",
         "url": "https://app.tavily.com/home",
-        "tools": ["web_search", "web_extract", "web_crawl"],
+        "tools": ["web_search", "web_extract"],
         "password": True,
         "category": "tool",
     },