Fix connection leaks causing crash on Android 9

- Added SafeSardineWrapper to properly close HTTP responses
- Prevents resource exhaustion after extended use (30-45 min)
- Added preemptive authentication to reduce 401 round-trips
- Added ProGuard rule for TextInclusionStrategy warnings
- Updated version to 1.7.1

Refs: #15

android/app/proguard-rules.pro

@@ -60,4 +60,8 @@
 -keep class * implements com.google.gson.JsonDeserializer
 
 # Keep your app's data classes
--keep class dev.dettmer.simplenotes.** { *; }
+-keep class dev.dettmer.simplenotes.** { *; }
+
+# v1.7.1: Suppress TextInclusionStrategy warnings on older Android versions
+# This class only exists on API 35+ but Compose handles the fallback gracefully
+-dontwarn android.text.Layout$TextInclusionStrategy