feat(providers): add DashScope and Bailian Coding providers with reasoning_content support

- Add DashScope (Qwen) native provider with tools+streaming fallback
- Add Bailian Coding provider with hardcoded model list (no /v1/models API)
- Parse reasoning_content in OpenAI-compat streaming/non-streaming responses
- Emit ChatEventThinking events in agent loop for thinking models
- Add vision support for DashScope (qwen3-vl)
- Fix provider form dialog not updating API base URL when switching types
- Update README provider count from 11+ to 13+

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/gateway_providers.go

@@ -66,6 +66,20 @@ func registerProviders(registry *providers.Registry, cfg *config.Config) {
 		registry.Register(providers.NewOpenAIProvider("perplexity", cfg.Providers.Perplexity.APIKey, "https://api.perplexity.ai", "sonar-pro"))
 		slog.Info("registered provider", "name", "perplexity")
 	}
+
+	if cfg.Providers.DashScope.APIKey != "" {
+		registry.Register(providers.NewDashScopeProvider(cfg.Providers.DashScope.APIKey, cfg.Providers.DashScope.APIBase, "qwen3-max"))
+		slog.Info("registered provider", "name", "dashscope")
+	}
+
+	if cfg.Providers.Bailian.APIKey != "" {
+		base := cfg.Providers.Bailian.APIBase
+		if base == "" {
+			base = "https://coding-intl.dashscope.aliyuncs.com/v1"
+		}
+		registry.Register(providers.NewOpenAIProvider("bailian", cfg.Providers.Bailian.APIKey, base, "qwen3.5-plus"))
+		slog.Info("registered provider", "name", "bailian")
+	}
 }
 
 // registerProvidersFromDB loads providers from Postgres and registers them.
@@ -84,6 +98,14 @@ func registerProvidersFromDB(registry *providers.Registry, provStore store.Provi
 		if p.ProviderType == store.ProviderAnthropicNative {
 			registry.Register(providers.NewAnthropicProvider(p.APIKey,
 				providers.WithAnthropicBaseURL(p.APIBase)))
+		} else if p.ProviderType == store.ProviderDashScope {
+			registry.Register(providers.NewDashScopeProvider(p.APIKey, p.APIBase, ""))
+		} else if p.ProviderType == store.ProviderBailian {
+			base := p.APIBase
+			if base == "" {
+				base = "https://coding-intl.dashscope.aliyuncs.com/v1"
+			}
+			registry.Register(providers.NewOpenAIProvider(p.Name, p.APIKey, base, "qwen3.5-plus"))
 		} else {
 			prov := providers.NewOpenAIProvider(p.Name, p.APIKey, p.APIBase, "")
 			if p.ProviderType == store.ProviderMiniMax {