chore(release): v1.7.2 - Critical Bugfixes & Performance Improvements

CRITICAL BUGFIXES:
- IMPL_014: JSON/Markdown Timestamp Sync - Server mtime source of truth
- IMPL_015: SyncStatus PENDING Fix - Set before JSON serialization
- IMPL_001: Deletion Tracker Race Condition - Mutex-based sync
- IMPL_002: ISO8601 Timezone Parsing - Multi-format support
- IMPL_003: Memory Leak Prevention - SafeSardine Closeable
- IMPL_004: E-Tag Batch Caching - ~50-100ms performance gain

FEATURES:
- Auto-updating timestamps in UI (every 30s)
- Performance optimizations for Staggered Grid scrolling

BUILD:
- versionCode: 19
- versionName: 1.7.2

This release prepares for a new cross-platform Markdown editor
(Web, Desktop Windows + Linux, Mobile) with proper JSON ↔ Markdown synchronization
and resolves critical sync issues for external editor integration.

android/app/build.gradle.kts

@@ -20,8 +20,8 @@ android {
         applicationId = "dev.dettmer.simplenotes"
         minSdk = 24
         targetSdk = 36
-        versionCode = 18  // 🔧 v1.7.1: Android 9 getForegroundInfo Fix (Issue #15)
-        versionName = "1.7.1"  // 🔧 v1.7.1: Android 9 getForegroundInfo Fix
+        versionCode = 19  // 🔧 v1.7.2: Critical Bugfixes (Timestamp Sync, SyncStatus, etc.)
+        versionName = "1.7.2"  // 🔧 v1.7.2: Critical Bugfixes
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }