Rename package to cy.hexor.furumi, add F-Droid compatibility

- Rename applicationId and all sources from com.example.furumi_android to cy.hexor.furumi
- Add WTFPL LICENSE
- Add fastlane metadata
- Add fdroiddata build metadata cy.hexor.furumi.yml
- Remove foojay-resolver plugin (blocked by F-Droid scanner)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/build.gradle.kts

@@ -6,11 +6,11 @@ plugins {
 }
 
 android {
-    namespace = "com.example.furumi_android"
+    namespace = "cy.hexor.furumi"
     compileSdk = 35
 
     defaultConfig {
-        applicationId = "com.example.furumi_android"
+        applicationId = "cy.hexor.furumi"
         minSdk = 24
         targetSdk = 35
         versionCode = 1