feat(providers): add Meituan LongCat catalog preset

Add LongCat-2.0 as a first-class OpenAI-compatible provider preset so it can be
selected by name in the setup wizard / `zero providers setup longcat` instead of
hand-entering a custom endpoint.

LongCat-2.0 is Meituan's open, OpenAI- and Anthropic-compatible model. This
wires the OpenAI-compatible transport:
  base URL: https://api.longcat.chat/openai  (Zero appends /chat/completions)
  model:    LongCat-2.0
  auth:     Bearer via LONGCAT_API_KEY

Purely additive — one descriptor plus its catalog/onboarding tests and a README
env-var line; no shared plumbing is touched, so existing providers are
unaffected. Placed with the other OpenAI-compatible third parties (after
moonshot), below the first-party providers.

Verified: go build / vet / test green (catalog + cli onboarding), gofmt clean,
and `zero providers catalog` lists the descriptor with the correct fields.
Endpoint is wired by-spec from LongCat's published docs; a live completion still
needs a real LONGCAT_API_KEY to confirm.

README.md

@@ -142,6 +142,13 @@ the key in the wizard:
 export OPENAI_API_KEY=sk-...
 export ANTHROPIC_API_KEY=...
 export GEMINI_API_KEY=...
+export LONGCAT_API_KEY=...
+```
+
+To configure Meituan LongCat (LongCat-2.0) directly, run:
+
+```bash
+zero providers setup longcat --set-active
 ```
 
 For local models, run Ollama or LM Studio and then use `zero setup` or

internal/cli/provider_catalog_onboarding_test.go

@@ -18,6 +18,7 @@ func TestProviderCatalogRuntimeProvidersShowOnboardingSetupHints(t *testing.T) {
 	}{
 		{id: "openai", name: "OpenAI", transport: "openai", defaultModel: "gpt-4.1"},
 		{id: "groq", name: "Groq", transport: "openai-compatible", defaultModel: "llama-3.3-70b-versatile"},
+		{id: "longcat", name: "LongCat", transport: "openai-compatible", defaultModel: "LongCat-2.0"},
 		{id: "ollama-cloud", name: "Ollama Cloud", transport: "openai-compatible", defaultModel: "qwen3-coder:480b"},
 		{id: "ollama", name: "Ollama Local", transport: "openai-compatible", defaultModel: "llama3.1"},
 	}
@@ -46,6 +47,21 @@ func TestProviderCatalogRuntimeProvidersShowOnboardingSetupHints(t *testing.T) {
 	}
 }
 
+func TestProviderCatalogLongCatRequiresAPIKey(t *testing.T) {
+	output := runProviderCatalogOnboarding(t)
+	block := providerCatalogOnboardingBlock(t, output, "longcat")
+
+	for _, want := range []string{
+		"requiresAuth=true",
+		"authEnvVars=LONGCAT_API_KEY",
+		"setup: zero providers setup longcat --set-active",
+	} {
+		if !strings.Contains(block, want) {
+			t.Fatalf("expected LongCat catalog block to contain %q, got:\n%s", want, block)
+		}
+	}
+}
+
 func TestProviderCatalogOllamaCloudRequiresAPIKey(t *testing.T) {
 	output := runProviderCatalogOnboarding(t)
 	block := providerCatalogOnboardingBlock(t, output, "ollama-cloud")

internal/providercatalog/catalog.go

@@ -123,6 +123,7 @@ var descriptors = []Descriptor{
 	openAICompat("together", "Together AI", "https://api.together.xyz/v1", "meta-llama/Llama-3.3-70B-Instruct-Turbo", []string{"TOGETHER_API_KEY"}),
 	openAICompat("dashscope", "DashScope", "https://dashscope-intl.aliyuncs.com/compatible-mode/v1", "qwen-plus", []string{"DASHSCOPE_API_KEY", "QWEN_API_KEY"}, "qwen"),
 	openAICompat("moonshot", "Moonshot AI", "https://api.moonshot.ai/v1", "kimi-k2-0905-preview", []string{"MOONSHOT_API_KEY"}, "kimi"),
+	openAICompat("longcat", "LongCat", "https://api.longcat.chat/openai", "LongCat-2.0", []string{"LONGCAT_API_KEY"}, "meituan longcat", "meituan", "longcat-2.0"),
 	openAICompat("nvidia-nim", "NVIDIA NIM", "https://integrate.api.nvidia.com/v1", "nvidia/llama-3.1-nemotron-70b-instruct", []string{"NVIDIA_API_KEY"}, "nvidia nim"),
 	anthropicCompat("minimax", "MiniMax", "https://api.minimax.io/anthropic", "MiniMax-M3", []string{"MINIMAX_API_KEY"}, "mini-max", "mini_max"),
 	openAICompat("mistral", "Mistral", "https://api.mistral.ai/v1", "mistral-large-latest", []string{"MISTRAL_API_KEY"}),

internal/providercatalog/catalog_test.go

@@ -23,6 +23,7 @@ var expectedCatalogIDs = []string{
 	"together",
 	"dashscope",
 	"moonshot",
+	"longcat",
 	"nvidia-nim",
 	"minimax",
 	"mistral",
@@ -99,6 +100,28 @@ func TestRecommendedProviderEndpoint(t *testing.T) {
 	}
 }
 
+func TestLongCatDescriptor(t *testing.T) {
+	descriptor, err := Require("longcat")
+	if err != nil {
+		t.Fatalf("Require(longcat) error = %v", err)
+	}
+	if descriptor.Name != "LongCat" {
+		t.Fatalf("Name = %q, want LongCat", descriptor.Name)
+	}
+	if descriptor.DefaultBaseURL != "https://api.longcat.chat/openai" {
+		t.Fatalf("DefaultBaseURL = %q, want LongCat OpenAI-compatible endpoint", descriptor.DefaultBaseURL)
+	}
+	if descriptor.DefaultModel != "LongCat-2.0" {
+		t.Fatalf("DefaultModel = %q, want LongCat-2.0", descriptor.DefaultModel)
+	}
+	if descriptor.Transport != TransportOpenAICompatible {
+		t.Fatalf("Transport = %q, want %q", descriptor.Transport, TransportOpenAICompatible)
+	}
+	if !reflect.DeepEqual(descriptor.AuthEnvVars, []string{"LONGCAT_API_KEY"}) {
+		t.Fatalf("AuthEnvVars = %#v, want LONGCAT_API_KEY", descriptor.AuthEnvVars)
+	}
+}
+
 func TestCatalogDescriptorsExposeRequiredDefaults(t *testing.T) {
 	for _, descriptor := range All() {
 		if descriptor.ID == "" {
@@ -267,7 +290,7 @@ func TestListByTransportPreservesCatalogOrder(t *testing.T) {
 		TransportBedrock:         {"bedrock"},
 		TransportVertex:          {"vertex"},
 		TransportAnthropicCompat: {"minimax", "custom-anthropic-compatible"},
-		TransportOpenAICompat:    {"gitlawb-opengateway", "ollama-cloud", "ollama", "lmstudio", "openrouter", "huggingface", "chatgpt", "groq", "deepseek", "together", "dashscope", "moonshot", "nvidia-nim", "mistral", "github", "xai", "venice", "xiaomi-mimo", "bankr", "zai", "kilocode", "opencode", "opencode-go", "atomic-chat", "chatgpt-proxy", "custom-openai-compatible"},
+		TransportOpenAICompat:    {"gitlawb-opengateway", "ollama-cloud", "ollama", "lmstudio", "openrouter", "huggingface", "chatgpt", "groq", "deepseek", "together", "dashscope", "moonshot", "longcat", "nvidia-nim", "mistral", "github", "xai", "venice", "xiaomi-mimo", "bankr", "zai", "kilocode", "opencode", "opencode-go", "atomic-chat", "chatgpt-proxy", "custom-openai-compatible"},
 	}
 
 	for transport, wantIDs := range cases {