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

src-tauri/tauri.conf.json

@@ -0,0 +1,36 @@
+{
+  "$schema": "https://schema.tauri.app/config/2",
+  "productName": "CrossRelay",
+  "version": "0.1.0",
+  "identifier": "cn.rutua.crossrelay",
+  "build": {
+    "frontendDist": "../dist",
+    "devUrl": "http://localhost:1420",
+    "beforeDevCommand": "npm run dev",
+    "beforeBuildCommand": "npm run build"
+  },
+  "app": {
+    "windows": [
+      {
+        "title": "CrossRelay",
+        "width": 1120,
+        "height": 760,
+        "minWidth": 960,
+        "minHeight": 640
+      }
+    ],
+    "security": {
+      "csp": "default-src 'self'; img-src 'self' data:; style-src 'self' 'unsafe-inline'; connect-src 'self' http://127.0.0.1:* http://localhost:*"
+    }
+  },
+  "bundle": {
+    "active": true,
+    "targets": ["nsis"],
+    "icon": [
+      "icons/32x32.png",
+      "icons/128x128.png",
+      "icons/128x128@2x.png",
+      "icons/icon.ico"
+    ]
+  }
+}