fix(tools): improve web search provider fallback (#2629)

- centralize web search provider readiness and resolution logic
- fall back when the configured provider is unavailable or invalid
- allow native-search-capable models to use built-in search without the client tool
- simplify the tools page and add direct access to web search settings
- add backend, agent, and integration tests for the new selection behavior

pkg/tools/integration_facade.go

@@ -4,6 +4,7 @@ import (
 	"github.com/modelcontextprotocol/go-sdk/mcp"
 
 	"github.com/sipeed/picoclaw/pkg/audio/tts"
+	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/media"
 	"github.com/sipeed/picoclaw/pkg/skills"
 	integrationtools "github.com/sipeed/picoclaw/pkg/tools/integration"
@@ -72,6 +73,18 @@ func GetPreferredWebSearchLanguage() string {
 	return integrationtools.GetPreferredWebSearchLanguage()
 }
 
+func WebSearchToolOptionsFromConfig(cfg *config.Config) WebSearchToolOptions {
+	return integrationtools.WebSearchToolOptionsFromConfig(cfg)
+}
+
+func WebSearchProviderReady(opts WebSearchToolOptions, name string) bool {
+	return integrationtools.WebSearchProviderReady(opts, name)
+}
+
+func ResolveWebSearchProviderName(opts WebSearchToolOptions, query string) (string, error) {
+	return integrationtools.ResolveWebSearchProviderName(opts, query)
+}
+
 func NewWebSearchTool(opts WebSearchToolOptions) (*WebSearchTool, error) {
 	return integrationtools.NewWebSearchTool(opts)
 }