p3: tavily parse errors degrade; retry DNS on search

A 200 with a bad Tavily body is tavily: error, not an empty success
that would cache for the hour. Upstream clients stay in the source
list if DNS is down at boot and retry the pin on Search; /healthz
lists them as unresolved until a pin lands.

internal/search/sources.go

@@ -30,6 +30,16 @@ func warnErr(name string, err error) string {
 	return name + ": error"
 }
 
+func pinErr(ctx context.Context, c *dial.Client, name string) string {
+	if c == nil {
+		return name + ": error"
+	}
+	if err := c.Ensure(ctx); err != nil {
+		return warnErr(name, err)
+	}
+	return ""
+}
+
 func readJSON(resp *http.Response, dest any) error {
 	defer resp.Body.Close()
 	if resp.StatusCode != 200 {
@@ -46,12 +56,16 @@ type SearxNG struct {
 }
 
 func (s *SearxNG) Name() string { return NameSearxNG }
+func (s *SearxNG) Ready() bool  { return s != nil && s.Client.Ready() }
+func (s *BraveLLM) Ready() bool { return s != nil && s.Client.Ready() }
 
 func (s *SearxNG) Search(ctx context.Context, query string, k int) SourceOut {
 	if s == nil || s.Client == nil {
 		return SourceOut{Warn: NameSearxNG + ": error"}
 	}
-	_ = s.Client.RefreshIfStale(ctx)
+	if w := pinErr(ctx, s.Client, NameSearxNG); w != "" {
+		return SourceOut{Warn: w}
+	}
 	base := strings.TrimRight(s.Client.URL.String(), "/")
 	u, err := url.Parse(base + "/search")
 	if err != nil {
@@ -110,7 +124,9 @@ func (s *BraveLLM) Search(ctx context.Context, query string, k int) SourceOut {
 	if s == nil || s.Client == nil {
 		return SourceOut{Warn: NameBraveLLM + ": error"}
 	}
-	_ = s.Client.RefreshIfStale(ctx)
+	if w := pinErr(ctx, s.Client, NameBraveLLM); w != "" {
+		return SourceOut{Warn: w}
+	}
 	u, err := url.Parse(s.Client.URL.String())
 	if err != nil {
 		return SourceOut{Warn: warnErr(NameBraveLLM, err)}