Add optional urlAllowlist config at tools.web level that restricts which
URLs can be accessed by web tools:
- Config types (types.tools.ts): Add urlAllowlist?: string[] to tools.web
- Zod schema: Add urlAllowlist field to ToolsWebSchema
- Schema help: Add help text for the new config fields
- web_search: Filter Brave search results by allowlist (provider=brave)
- web_fetch: Block URLs not matching allowlist before fetching
- ssrf.ts: Export normalizeHostnameAllowlist and matchesHostnameAllowlist
URL matching supports:
- Exact domain match (example.com)
- Wildcard patterns (*.github.com)
When urlAllowlist is not configured, all URLs are allowed (backwards compatible).
Tests: Add web-tools.url-allowlist.test.ts with 23 tests covering:
- URL allowlist resolution from config
- Wildcard pattern matching
- web_fetch error response format
- Brave search result filtering
