chore: move api keys and client url's to new apikeys.properties to …

…respect best practices

Moved API keys for Supabase and client URLs for Supabase and PowerSync to a new file called `apikeys.properties` instead of having them in `local.properties`.
This respects the Gradle properties files recommendations [here](https://developer.android.com/build#properties-files), saying:

> Caution: The local.properties file is reserved for properties specific to the Android Gradle plugin. Putting your own values in this file can cause problems. If you need to define your own local properties, create a separate properties file and manually load it.

!! This `apikeys.properties` should never be uploaded to VCS !!

.gitignore

@@ -2,6 +2,7 @@
 .DS_Store
 .gradle
 /local.properties
+/apikeys.properties
 /build
 /captures
 .externalNativeBuild

app/build.gradle.kts

@@ -19,14 +19,14 @@ android {
   namespace = "com.android.periodpals"
   compileSdk = 34
 
-  // Load the API key from local.properties
-  val localProperties = Properties()
-  val localPropertiesFile = rootProject.file("local.properties")
+  // Load the API key from apikeys.properties
+  val apikeysProperties = Properties()
+  val localPropertiesFile = rootProject.file("apikeys.properties")
   if (localPropertiesFile.exists()) {
-    localProperties.load(FileInputStream(localPropertiesFile))
+    apikeysProperties.load(FileInputStream(localPropertiesFile))
   }
-  val supabaseUrl = localProperties.getProperty("SUPABASE_URL")
-  val supabaseKey = localProperties.getProperty("SUPABASE_KEY")
+  val supabaseUrl = apikeysProperties.getProperty("SUPABASE_URL") ?: ""
+  val supabaseKey = apikeysProperties.getProperty("SUPABASE_KEY") ?: ""
 
   defaultConfig {
     applicationId = "com.android.periodpals"