v1.0.4: Fix tiptapToMarkdown JsonElement type casting

- tiptapToMarkdown used JsonObject.asMap() which returns Map<String, JsonElement>
- All 'as? String' casts silently failed (JsonPrimitive != String), returning empty
- Now uses Gson TypeToken<Map<String, Any?>> for proper raw type deserialization
- contentToMarkdown now handles Map types directly without serialize roundtrip

app/build.gradle.kts

@@ -20,8 +20,8 @@ android {
         applicationId = "com.docmost.app"
         minSdk = 26
         targetSdk = 34
-        versionCode = 4
-        versionName = "1.0.3"
+        versionCode = 5
+        versionName = "1.0.4"
     }
 
     signingConfigs {