make yarn build the data-approval build and drop mal-* naming

The build script chain still carried legacy names from the original
malaria report fork (nhwa-build-folder, mal-icon.png, mal-favicon.ico,
manifest_mal.json) even though this repo is now the generic Data
Approval Extended app. Consolidate the build pipeline so plain
'yarn build' produces the app zip, and rename or drop the leftover
mal-prefixed assets and scripts.

- Collapse build-folder / nhwa-build-folder / build-default into a
  single build-folder + build pair driven by yarn build.
- Rename mal-icon.png to app-icon.png and update the package.json
  manifest.webapp icon reference accordingly.
- Delete public/mal-favicon.ico and public/manifest_mal.json — they
  were copied into build/ only to be removed again by the cleanup
  step, so they had no effect on the produced app.
- Delete src/scripts/build.ts, which was no longer wired into any
  npm script and still referenced a non-existent yarn nhwa-build.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Ramon-Jimenez

mal-icon.png app-icon.pngmal-icon.png renamed to app-icon.png

@@ -55,10 +55,8 @@
         "start": "react-scripts start",
         "craco-start": "craco start",
         "prebuild": "yarn localize && yarn test",
-        "build-folder": "rm -rf build/ && d2-manifest package.json manifest.webapp && react-scripts build && yarn run manifest && cp -r i18n icon.png build",
-        "build-default": "REACT_APP_DHIS2_BASE_URL='' REACT_APP_DHIS2_AUTH='' yarn build-folder && rm -f $npm_package_name.zip && cd build && rm -f manifest_mal.json mal-favicon.ico && zip --quiet -r ../$npm_package_name.zip *",
-        "nhwa-build-folder": "rm -rf build/ && d2-manifest package.json manifest.webapp && react-scripts build && yarn run manifest && cp -r i18n mal-icon.png build",
-        "build": "REACT_APP_DHIS2_BASE_URL='' REACT_APP_DHIS2_AUTH='' yarn nhwa-build-folder && rm -f $npm_package_name.zip && cd build && rm -f manifest.json mal-favicon.ico && zip --quiet -r ../$npm_package_name.zip *",
+        "build-folder": "rm -rf build/ && d2-manifest package.json manifest.webapp && react-scripts build && yarn run manifest && cp -r i18n app-icon.png build",
+        "build": "REACT_APP_DHIS2_BASE_URL='' REACT_APP_DHIS2_AUTH='' yarn build-folder && rm -f $npm_package_name.zip && cd build && rm -f manifest.json && zip --quiet -r ../$npm_package_name.zip *",
         "test": "jest --passWithNoTests",
         "lint": "eslint src --ext .js,.jsx,.ts,.tsx",
         "eject": "react-scripts eject",
@@ -131,7 +129,7 @@
         "name": "Data Approval Extended",
         "description": "Data Approval Extended",
         "icons": {
-            "48": "mal-icon.png"
+            "48": "app-icon.png"
         },
         "developer": {
             "url": "https://www.eyeseetea.com/",