Improve release scripts and make workflows manual

Redirect script informational/warning output to stderr and improve robustness of release tooling. Changes include:

- Redirect many echo messages to stderr so scripts can emit machine-readable output on stdout.
- Extract-release-notes: better parsing of CHANGELOG entries (tries v-prefixed and non-prefixed headings, cleaner note formatting) and improved fallbacks when changelog is missing.
- Extract-version: accept versions with +build or -suffix, add diagnostic output when pubspec is missing, and tighten validation.
- Setup/verify APK signing: more consistent stderr logging and clearer warnings; ensure keystore decoding/logging is visible.
- Minor script usage message fixes (generate-tag-name, attach-apk-to-release).
- CI/workflows: change backend-foundation, mobile-ci, and web-quality triggers to workflow_dispatch (manual runs); update product-release (make scripts step label emoji, remove node cache lines, bump Flutter to 3.38.x).

These changes improve CI reliability, make scripts friendlier for automated consumers, and fix release note/version parsing edge cases.

.github/workflows/backend-foundation.yml

@@ -1,14 +1,7 @@
 name: Backend Foundation
 
 on:
-  pull_request:
-    branches:
-      - dev
-      - main
-  push:
-    branches:
-      - dev
-      - main
+  workflow_dispatch:
 
 jobs:
   backend-foundation-makefile:

.github/workflows/mobile-ci.yml

@@ -1,16 +1,7 @@
 name: Mobile CI
 
 on:
-  pull_request:
-    paths:
-      - 'apps/mobile/**'
-      - '.github/workflows/mobile-ci.yml'
-  push:
-    branches:
-      - main
-    paths:
-      - 'apps/mobile/**'
-      - '.github/workflows/mobile-ci.yml'
+  workflow_dispatch:
 
 jobs:
   detect-changes:

.github/workflows/product-release.yml

@@ -45,7 +45,7 @@ jobs:
         with:
           fetch-depth: 0
           
-      - name: <EFBFBD> Make scripts executable
+      - name: 🏃🏾‍♂️ Make scripts executable
         run: |
           chmod +x .github/scripts/*.sh
           echo "✅ Scripts are now executable"
@@ -165,8 +165,6 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: '20'
-          cache: 'npm'
-          cache-dependency-path: 'backend/*/package-lock.json'
           
       - name: 🔥 Install Firebase CLI
         run: |
@@ -184,7 +182,7 @@ jobs:
       - name: 🐦 Setup Flutter
         uses: subosito/flutter-action@v2
         with:
-          flutter-version: '3.24.5'
+          flutter-version: '3.38.x'
           channel: 'stable'
           cache: true
           

.github/workflows/web-quality.yml

@@ -1,14 +1,7 @@
 name: Web Quality
 
 on:
-  pull_request:
-    branches:
-      - dev
-      - main
-  push:
-    branches:
-      - dev
-      - main
+  workflow_dispatch:
 
 jobs:
   web-quality: