init: 汇率换算工具小程序骨架

- 两个页面：首页（双向换算）+ 汇率总览（一对多）
- 基础项目结构和配置
- AppID 待填入

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

project.config.json

@@ -0,0 +1,33 @@
+{
+  "miniprogramRoot": "miniprogram/",
+  "appid": "",
+  "projectname": "currency-converter",
+  "description": "汇率换算工具",
+  "setting": {
+    "urlCheck": true,
+    "es6": true,
+    "enhance": true,
+    "postcss": true,
+    "preloadBackgroundData": false,
+    "minified": true,
+    "newFeature": true,
+    "coverView": true,
+    "nodeModules": false,
+    "autoAudits": false,
+    "showShadowRootInWxmlPanel": true,
+    "scopeDataCheck": false,
+    "checkInvalidKey": true,
+    "checkSiteMap": true,
+    "uploadWithSourceMap": true,
+    "compileHotReLoad": false,
+    "lazyloadPlaceholderEnable": false,
+    "useMultiFrameRuntime": true,
+    "babelSetting": {
+      "ignore": [],
+      "disablePlugins": [],
+      "outputPath": ""
+    }
+  },
+  "compileType": "miniprogram",
+  "condition": {}
+}