🐛 v1.2.1: Markdown Initial Export Bugfix + URL Normalization + GitHub Workflow Fix

## 🐛 Fixed
- Initial Markdown export: Existing notes now exported when Desktop Integration activated
- Markdown directory structure: Files now land correctly in /notes-md/
- JSON URL normalization: Smart detection for both Root-URL and /notes-URL
- GitHub release notes: Fixed language order (DE primary, EN collapsible) and emoji

## ✨ Improved
- Settings UI: Example URL shows /notes instead of /webdav
- Server config: Enter only base URL (app adds /notes/ and /notes-md/ automatically)
- Flexible URL input: Both http://server/ and http://server/notes/ work
- Changelogs: Shortened for F-Droid 500 char limit

## 🔧 Technical
- getNotesUrl() helper with smart /notes/ detection
- getMarkdownUrl() simplified to use getNotesUrl()
- All JSON operations updated to use normalized URLs
- exportAllNotesToMarkdown() with progress callback
- Workflow: Swapped CHANGELOG_DE/EN, replaced broken emoji with 🌍

versionCode: 6
versionName: 1.2.1

android/app/src/main/res/layout/activity_settings.xml

@@ -109,7 +109,7 @@
                         style="@style/Widget.Material3.TextInputLayout.OutlinedBox"
                         app:startIconDrawable="@android:drawable/ic_menu_compass"
                         app:endIconMode="clear_text"
-                        app:helperText="z.B. http://192.168.0.188:8080/webdav"
+                        app:helperText="z.B. http://192.168.0.188:8080/notes"
                         app:helperTextEnabled="true"
                         app:boxCornerRadiusTopStart="12dp"
                         app:boxCornerRadiusTopEnd="12dp"