🐛 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/build.gradle.kts

@@ -17,8 +17,8 @@ android {
         applicationId = "dev.dettmer.simplenotes"
         minSdk = 24
         targetSdk = 36
-        versionCode = 5  // 🔥 v1.2.0: Local Backup + Markdown Desktop Integration
-        versionName = "1.2.0"  // 🔥 v1.2.0: Backup/Restore + Joplin/Obsidian Support
+        versionCode = 6  // 🐛 v1.2.1: Markdown Initial Export Bugfix
+        versionName = "1.2.1"  // 🐛 v1.2.1: Markdown Initial Export Bugfix
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"