Refactor GitHub Actions workflows (#1023)

* Unify release workflows and add chart/mobile wrappers

* Update chart CI to kube 1.25

* Fetch tagged commit before pushing release branch

* Old `azure/setup-helm`

* Base chart dispatch version on existing chart tags

* `grep` failure with `pipefail` bypasses the user-friendly error message

* `gh-pages` push lacks retry logic

* Auto-incremented chart tag collision

* `grep -Ev` pipeline will crash

* Missed one

.github/workflows/flutter-build.yml

@@ -1,28 +1,6 @@
 name: Flutter Mobile Build
 
 on:
-  push:
-    branches:
-      - main
-    tags:
-      - 'v*'
-    paths:
-      - 'mobile/lib/**'
-      - 'mobile/android/**'
-      - 'mobile/ios/**'
-      - 'mobile/pubspec.yaml'
-      - 'public/android-chrome-*.png'
-      - 'public/apple-touch-icon.png'
-      - '.github/workflows/flutter-build.yml'
-  pull_request:
-    paths:
-      - 'mobile/lib/**'
-      - 'mobile/android/**'
-      - 'mobile/ios/**'
-      - 'mobile/pubspec.yaml'
-      - 'public/android-chrome-*.png'
-      - 'public/apple-touch-icon.png'
-      - '.github/workflows/flutter-build.yml'
   workflow_call:
   workflow_dispatch:
 
@@ -189,4 +167,4 @@ jobs:
           path: |
             mobile/build/ios/iphoneos/Runner.app
             mobile/build/ios-build-info.txt
-          retention-days: 30
+          retention-days: 30