feat(programs): Excel 模板下载 + .xlsx 解析导入

- 新增 excel 4.0.6 / path_provider 2.1.5 依赖
- ExcelTemplateService：生成 Programs + Steps 双表模板（保存到应用文档目录）
- ExcelImportService：解析 .xlsx 并写入数据库，跳过已存在 code、按 program_code 关联步骤
- programs_page 顶部新增「下载模板」按钮，导入按钮改用 Excel 解析
- 移除被取代的 program_import_service.dart
- AppLocalizations 新增 downloadTemplate 键
- 验证：flutter analyze 无新增 issue；flutter build apk --debug 通过

pubspec.lock

@@ -25,6 +25,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.13.4"
+  archive:
+    dependency: transitive
+    description:
+      name: archive
+      sha256: cb6a278ef2dbb298455e1a713bda08524a175630ec643a242c399c932a0a1f7d
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.6.1"
   args:
     dependency: transitive
     description:
@@ -89,6 +97,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.2"
+  code_assets:
+    dependency: transitive
+    description:
+      name: code_assets
+      sha256: bf394f466ba9205f1812a0433b392d6af280f155f56651eda7c18cc32ed493b8
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.1"
   collection:
     dependency: transitive
     description:
@@ -169,6 +185,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.1.1"
+  equatable:
+    dependency: transitive
+    description:
+      name: equatable
+      sha256: "3e0141505477fd8ad55d6eb4e7776d3fe8430be8e497ccb1521370c3f21a3e2b"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.8"
+  excel:
+    dependency: "direct main"
+    description:
+      name: excel
+      sha256: "1a15327dcad260d5db21d1f6e04f04838109b39a2f6a84ea486ceda36e468780"
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.0.6"
   fake_async:
     dependency: transitive
     description:
@@ -277,6 +309,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "15.1.3"
+  hooks:
+    dependency: transitive
+    description:
+      name: hooks
+      sha256: "9a62a50b50b769a737bc0a8ff381f333529df3ab746b2f6b02e83760231455ba"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.2"
   hotreloader:
     dependency: transitive
     description:
@@ -293,6 +333,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.20.2"
+  jni:
+    dependency: transitive
+    description:
+      name: jni
+      sha256: c2230682d5bc2362c1c9e8d3c7f406d9cbba23ab3f2e203a025dd47e0fb2e68f
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
+  jni_flutter:
+    dependency: transitive
+    description:
+      name: jni_flutter
+      sha256: "8b59e590786050b1cd866677dddaf76b1ade5e7bc751abe04b86e84d379d3ba6"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.1"
   json_annotation:
     dependency: transitive
     description:
@@ -365,6 +421,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.17.0"
+  objective_c:
+    dependency: transitive
+    description:
+      name: objective_c
+      sha256: "6cb691c686fa2838c6deb34980d426145c2a5d537491cb83d463c33cdbc726ed"
+      url: "https://pub.dev"
+    source: hosted
+    version: "9.4.1"
   package_config:
     dependency: transitive
     description:
@@ -381,6 +445,30 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
+  path_provider:
+    dependency: "direct main"
+    description:
+      name: path_provider
+      sha256: "50c5dd5b6e1aaf6fb3a78b33f6aa3afca52bf903a8a5298f53101fdaee55bbcd"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.5"
+  path_provider_android:
+    dependency: transitive
+    description:
+      name: path_provider_android
+      sha256: "69cbd515a62b94d32a7944f086b2f82b4ac40a1d45bebfc00813a430ab2dabcd"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.1"
+  path_provider_foundation:
+    dependency: transitive
+    description:
+      name: path_provider_foundation
+      sha256: "2a376b7d6392d80cd3705782d2caa734ca4727776db0b6ec36ef3f1855197699"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.6.0"
   path_provider_linux:
     dependency: transitive
     description:
@@ -405,6 +493,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.3.0"
+  petitparser:
+    dependency: transitive
+    description:
+      name: petitparser
+      sha256: "91bd59303e9f769f108f8df05e371341b15d59e995e6806aefab827b58336675"
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.2"
   platform:
     dependency: transitive
     description:
@@ -437,6 +533,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.5.0"
+  record_use:
+    dependency: transitive
+    description:
+      name: record_use
+      sha256: "2551bd8eecfe95d14ae75f6021ad0248be5c27f138c2ec12fcb52b500b3ba1ed"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.0"
   riverpod:
     dependency: transitive
     description:
@@ -714,6 +818,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.0"
+  xml:
+    dependency: transitive
+    description:
+      name: xml
+      sha256: "971043b3a0d3da28727e40ed3e0b5d18b742fa5a68665cca88e74b7876d5e025"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.6.1"
   yaml:
     dependency: transitive
     description:
@@ -724,4 +836,4 @@ packages:
     version: "3.1.3"
 sdks:
   dart: ">=3.11.5 <4.0.0"
-  flutter: ">=3.38.0"
+  flutter: ">=3.38.4"