Refactor: remove Compose prefix from Activity names

- Rename ComposeActivity to MainActivity
- Rename EditProfileComposeActivity to EditProfileActivity
- Rename NewProfileComposeActivity to NewProfileActivity
- Rename GroupsComposeActivity to GroupsActivity
- Move data models to compose/model package
- Update all references in AndroidManifest.xml and source files

app/src/main/java/io/nekohasekai/sfa/LauncherActivity.kt

@@ -3,14 +3,14 @@ package io.nekohasekai.sfa
 import android.app.Activity
 import android.content.Intent
 import android.os.Bundle
-import io.nekohasekai.sfa.compose.ComposeActivity
+import io.nekohasekai.sfa.compose.MainActivity
 
 class LauncherActivity : Activity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         val launchIntent =
-            Intent(this, ComposeActivity::class.java).apply {
+            Intent(this, MainActivity::class.java).apply {
                 intent?.let {
                     action = it.action
                     data = it.data