fix v0 skills migration preserving github registry defaults

pkg/config/config_old.go

@@ -984,13 +984,20 @@ func (v *skillsGithubConfigV0) ToSkillsGithubConfig() SkillsGithubConfig {
 }
 
 func (v *skillsToolsConfigV0) ToSkillsToolsConfig() SkillsToolsConfig {
+	cfg := DefaultConfig().Tools.Skills
 	clawHub := v.Registries.ClawHub.ToSkillRegistryConfig()
-	github := v.Github.ToSkillsGithubConfig()
+	cfg.ToolConfig = v.ToolConfig
-	return SkillsToolsConfig{
+	cfg.Registries.Set(clawHub.Name, clawHub)
-		ToolConfig:            v.ToolConfig,
+	if v.Github.BaseURL != "" {
-		Registries:            SkillsRegistriesConfig{&clawHub},
+		cfg.Github.BaseURL = v.Github.BaseURL
-		Github:                github,
-		MaxConcurrentSearches: v.MaxConcurrentSearches,
-		SearchCache:           v.SearchCache,
 	}
+	if v.Github.Token != "" {
+		cfg.Github.Token = *NewSecureString(v.Github.Token)
+	}
+	if v.Github.Proxy != "" {
+		cfg.Github.Proxy = v.Github.Proxy
+	}
+	cfg.MaxConcurrentSearches = v.MaxConcurrentSearches
+	cfg.SearchCache = v.SearchCache
+	return cfg
 }

pkg/config/migration_integration_test.go

@@ -1118,6 +1118,17 @@ func TestLoadConfig_V0MigrateProducesV2(t *testing.T) {
 	if !modelEnabled("local-model") {
 		t.Error("local-model from V0 should be enabled")
 	}
+
+	githubRegistry, ok := cfg.Tools.Skills.Registries.Get("github")
+	if !ok {
+		t.Fatal("expected default github skills registry to survive V0 migration")
+	}
+	if !githubRegistry.Enabled {
+		t.Error("github skills registry should remain enabled after V0 migration")
+	}
+	if githubRegistry.BaseURL != "https://github.com" {
+		t.Errorf("github registry base_url = %q, want %q", githubRegistry.BaseURL, "https://github.com")
+	}
 }
 
 // TestLoadConfig_UnsupportedVersion verifies that unsupported versions return an error.