CrossRelay stage 0+1: Go gateway with Anthropic<->Chat Completions relay, Tauri shell, bilingual management UI

- Go gateway (stdlib only): /v1/messages non-stream + SSE, /v1/messages/count_tokens,
  management API /api/* (providers CRUD, apply/restore, settings, backups, logs)
- Protocol conversion: Anthropic Messages <-> Chat Completions with a streaming
  state machine keyed by content block index (text, tool_use, parallel calls)
- ~/.claude/settings.json guarded read/write: timestamped backups, managed env
  keys only, one-click restore
- Tauri 2 shell: spawns the gateway sidecar, parses the random port from stdout,
  stdin pipe watchdog prevents orphans, kills the child on exit
- React frontend: Dashboard/Providers/Settings, zh-CN + en-US, TanStack Query
- Tests: Go table-driven + httptest integration (all green), vitest + RTL

internal/presets/presets.go

@@ -0,0 +1,56 @@
+// Package presets holds the built-in upstream provider templates.
+package presets
+
+import "gitea.rutua.cn/kate522/CrossRelay/internal/config"
+
+// Preset is a ready-made provider template. Model names reflect each
+// vendor's catalog as of 2026-10 and can be edited per provider.
+type Preset struct {
+	Key     string        `json:"key"`
+	BaseURL string        `json:"base_url"`
+	Models  config.Models `json:"models"`
+}
+
+// All lists the built-in presets.
+var All = []Preset{
+	{
+		Key:     "deepseek",
+		BaseURL: "https://api.deepseek.com/v1",
+		Models: config.Models{
+			Default: "deepseek-chat",
+			Sonnet:  "deepseek-chat",
+			Haiku:   "deepseek-chat",
+			Opus:    "deepseek-chat",
+		},
+	},
+	{
+		Key:     "moonshot",
+		BaseURL: "https://api.moonshot.cn/v1",
+		Models: config.Models{
+			Default: "kimi-k2-0905-preview",
+			Sonnet:  "kimi-k2-0905-preview",
+			Haiku:   "kimi-k2-0905-preview",
+			Opus:    "kimi-k2-0905-preview",
+		},
+	},
+	{
+		Key:     "zhipu",
+		BaseURL: "https://open.bigmodel.cn/api/paas/v4",
+		Models: config.Models{
+			Default: "glm-4.6",
+			Sonnet:  "glm-4.6",
+			Haiku:   "glm-4.6",
+			Opus:    "glm-4.6",
+		},
+	},
+}
+
+// ByKey looks up a preset by its key.
+func ByKey(key string) (Preset, bool) {
+	for _, p := range All {
+		if p.Key == key {
+			return p, true
+		}
+	}
+	return Preset{}, false
+}