feat(04-02): add downloadFile and downloadZip utility functions

- src/utils/downloadFile.ts: Blob + createObjectURL + anchor click download
- src/utils/downloadZip.ts: JSZip archive builder with same Blob download pattern
- npm install jszip ^3.10.1 (only new runtime dependency in phase 4)

package-lock.json

@@ -9,6 +9,7 @@
       "version": "0.0.0",
       "dependencies": {
         "@hookform/resolvers": "^5.2.2",
+        "jszip": "^3.10.1",
         "react": "^18.3.1",
         "react-dom": "^18.3.1",
         "react-hook-form": "^7.72.0",
@@ -2189,6 +2190,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/core-util-is": {
+      "version": "1.0.3",
+      "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.3.tgz",
+      "integrity": "sha512-ZQBvi1DcpJ4GDqanjucZ2Hj3wEO5pZDS89BWbkcrvdxksJorwUDDZamX9ldFkp9aw2lmBDLgkObEA4DWNJ9FYQ==",
+      "license": "MIT"
+    },
     "node_modules/css-tree": {
       "version": "3.2.1",
       "resolved": "https://registry.npmjs.org/css-tree/-/css-tree-3.2.1.tgz",
@@ -2452,6 +2459,18 @@
         "node": "^20.19.0 || ^22.12.0 || >=24.0.0"
       }
     },
+    "node_modules/immediate": {
+      "version": "3.0.6",
+      "resolved": "https://registry.npmjs.org/immediate/-/immediate-3.0.6.tgz",
+      "integrity": "sha512-XXOFtyqDjNDAQxVfYxuF7g9Il/IbWmmlQg2MYKOH8ExIT1qg6xc4zyS3HaEEATgs1btfzxq15ciUiY7gjSXRGQ==",
+      "license": "MIT"
+    },
+    "node_modules/inherits": {
+      "version": "2.0.4",
+      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
+      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
+      "license": "ISC"
+    },
     "node_modules/is-potential-custom-element-name": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/is-potential-custom-element-name/-/is-potential-custom-element-name-1.0.1.tgz",
@@ -2459,6 +2478,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/isarray": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/isarray/-/isarray-1.0.0.tgz",
+      "integrity": "sha512-VLghIWNM6ELQzo7zwmcg0NmTVyWKYjvIeM83yjp0wRDTmUnrM678fQbcKBo6n2CJEF0szoG//ytg+TKla89ALQ==",
+      "license": "MIT"
+    },
     "node_modules/jiti": {
       "version": "2.6.1",
       "resolved": "https://registry.npmjs.org/jiti/-/jiti-2.6.1.tgz",
@@ -2552,6 +2577,27 @@
         "node": ">=6"
       }
     },
+    "node_modules/jszip": {
+      "version": "3.10.1",
+      "resolved": "https://registry.npmjs.org/jszip/-/jszip-3.10.1.tgz",
+      "integrity": "sha512-xXDvecyTpGLrqFrvkrUSoxxfJI5AH7U8zxxtVclpsUtMCq4JQ290LY8AW5c7Ggnr/Y/oK+bQMbqK2qmtk3pN4g==",
+      "license": "(MIT OR GPL-3.0-or-later)",
+      "dependencies": {
+        "lie": "~3.3.0",
+        "pako": "~1.0.2",
+        "readable-stream": "~2.3.6",
+        "setimmediate": "^1.0.5"
+      }
+    },
+    "node_modules/lie": {
+      "version": "3.3.0",
+      "resolved": "https://registry.npmjs.org/lie/-/lie-3.3.0.tgz",
+      "integrity": "sha512-UaiMJzeWRlEujzAuw5LokY1L5ecNQYZKfmyZ9L7wDHb/p5etKaxXhohBcrw0EYby+G/NA52vRSN4N39dxHAIwQ==",
+      "license": "MIT",
+      "dependencies": {
+        "immediate": "~3.0.5"
+      }
+    },
     "node_modules/lightningcss": {
       "version": "1.32.0",
       "resolved": "https://registry.npmjs.org/lightningcss/-/lightningcss-1.32.0.tgz",
@@ -2918,6 +2964,12 @@
       ],
       "license": "MIT"
     },
+    "node_modules/pako": {
+      "version": "1.0.11",
+      "resolved": "https://registry.npmjs.org/pako/-/pako-1.0.11.tgz",
+      "integrity": "sha512-4hLB8Py4zZce5s4yd9XzopqwVv/yGNhV1Bl8NTmCq1763HeK2+EwVTv+leGeL13Dnh2wfbqowVPXCIO0z4taYw==",
+      "license": "(MIT AND Zlib)"
+    },
     "node_modules/parse5": {
       "version": "8.0.0",
       "resolved": "https://registry.npmjs.org/parse5/-/parse5-8.0.0.tgz",
@@ -3002,6 +3054,12 @@
         "node": "^10.13.0 || ^12.13.0 || ^14.15.0 || >=15.0.0"
       }
     },
+    "node_modules/process-nextick-args": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.1.tgz",
+      "integrity": "sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag==",
+      "license": "MIT"
+    },
     "node_modules/punycode": {
       "version": "2.3.1",
       "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.1.tgz",
@@ -3070,6 +3128,21 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/readable-stream": {
+      "version": "2.3.8",
+      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-2.3.8.tgz",
+      "integrity": "sha512-8p0AUk4XODgIewSi0l8Epjs+EVnWiK7NoDIEGU0HhE7+ZyY8D1IMY7odu5lRrFXGg71L15KG8QrPmum45RTtdA==",
+      "license": "MIT",
+      "dependencies": {
+        "core-util-is": "~1.0.0",
+        "inherits": "~2.0.3",
+        "isarray": "~1.0.0",
+        "process-nextick-args": "~2.0.0",
+        "safe-buffer": "~5.1.1",
+        "string_decoder": "~1.1.1",
+        "util-deprecate": "~1.0.1"
+      }
+    },
     "node_modules/require-from-string": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/require-from-string/-/require-from-string-2.0.2.tgz",
@@ -3125,6 +3198,12 @@
         "fsevents": "~2.3.2"
       }
     },
+    "node_modules/safe-buffer": {
+      "version": "5.1.2",
+      "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
+      "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g==",
+      "license": "MIT"
+    },
     "node_modules/saxes": {
       "version": "6.0.0",
       "resolved": "https://registry.npmjs.org/saxes/-/saxes-6.0.0.tgz",
@@ -3157,6 +3236,12 @@
         "semver": "bin/semver.js"
       }
     },
+    "node_modules/setimmediate": {
+      "version": "1.0.5",
+      "resolved": "https://registry.npmjs.org/setimmediate/-/setimmediate-1.0.5.tgz",
+      "integrity": "sha512-MATJdZp8sLqDl/68LfQmbP8zKPLQNV6BIZoIgrscFDQ+RsvK/BxeDQOgyxKKoh0y/8h3BqVFnCqQ/gd+reiIXA==",
+      "license": "MIT"
+    },
     "node_modules/siginfo": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/siginfo/-/siginfo-2.0.0.tgz",
@@ -3188,6 +3273,15 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/string_decoder": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.1.1.tgz",
+      "integrity": "sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==",
+      "license": "MIT",
+      "dependencies": {
+        "safe-buffer": "~5.1.0"
+      }
+    },
     "node_modules/symbol-tree": {
       "version": "3.2.4",
       "resolved": "https://registry.npmjs.org/symbol-tree/-/symbol-tree-3.2.4.tgz",
@@ -3361,6 +3455,12 @@
         "browserslist": ">= 4.21.0"
       }
     },
+    "node_modules/util-deprecate": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
+      "integrity": "sha512-EPD5q1uXyFxJpCrLnCc1nHnq3gOa6DZBocAIiI2TaSCA7VCJ1UJDMagCzIkXNsUYfD1daK//LTEQ8xiIbrHtcw==",
+      "license": "MIT"
+    },
     "node_modules/vite": {
       "version": "6.4.1",
       "resolved": "https://registry.npmjs.org/vite/-/vite-6.4.1.tgz",

package.json

@@ -12,6 +12,7 @@
   },
   "dependencies": {
     "@hookform/resolvers": "^5.2.2",
+    "jszip": "^3.10.1",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-hook-form": "^7.72.0",

src/utils/downloadFile.ts

@@ -0,0 +1,12 @@
+// src/utils/downloadFile.ts
+// Triggers a browser file download from a string.
+// Pattern: MDN URL.createObjectURL — https://developer.mozilla.org/en-US/docs/Web/API/URL/createObjectURL_static
+export function downloadFile(content: string, filename: string): void {
+  const blob = new Blob([content], { type: 'text/plain;charset=utf-8' });
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement('a');
+  a.href = url;
+  a.download = filename;
+  a.click();
+  URL.revokeObjectURL(url);
+}

src/utils/downloadZip.ts

@@ -0,0 +1,21 @@
+// src/utils/downloadZip.ts
+// Builds a ZIP archive from file entries and triggers download.
+// Pattern: JSZip official docs — https://stuk.github.io/jszip/documentation/examples/download-zip-file.html
+import JSZip from 'jszip';
+
+export async function downloadZip(
+  files: { name: string; content: string }[],
+  zipName: string
+): Promise<void> {
+  const zip = new JSZip();
+  for (const { name, content } of files) {
+    zip.file(name, content);
+  }
+  const blob = await zip.generateAsync({ type: 'blob' });
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement('a');
+  a.href = url;
+  a.download = zipName;
+  a.click();
+  URL.revokeObjectURL(url);
+}