feat(web): 纳入 @lunar/core 排盘核心并批准 esbuild 构建脚本

web-commercial 依赖 file:../web/packages/core，此前 web/ 被 gitignore，
干净 worktree 无法构建商业前端；同时将 esbuild 加入 allowBuilds。

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web/packages/core/package.json

@@ -0,0 +1,34 @@
+{
+  "name": "@lunar/core",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Core calculation engine for lunar calendar app",
+  "type": "module",
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js",
+      "require": "./dist/index.cjs"
+    }
+  },
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "dev": "tsup --watch",
+    "build": "tsup",
+    "test": "vitest run",
+    "lint": "eslint .",
+    "clean": "rm -rf dist"
+  },
+  "dependencies": {
+    "tyme4ts": "^1.5.1"
+  },
+  "devDependencies": {
+    "tsup": "^8.4.0",
+    "typescript": "^5.7.0",
+    "vitest": "^4.1.10"
+  }
+}