feat: Add first-launch server URL input dialog

Implements a setup dialog on first game launch that allows users to enter
their custom community server URL without rebuilding the APK.

Features:
- Server URL input dialog on first launch
- URL validation (format check)
- Connection test button
- SharedPreferences storage
- Priority: SharedPreferences > AndroidManifest.xml > EA defaults
- Activity restart flow for applying configuration

New files:
- CommunityServerManager.smali (URL management)
- ServerSetupActivity.smali + 4 inner classes (dialog UI)
- res/layout/activity_server_setup.xml (layout)
- SERVER-URL-INPUT-IMPLEMENTATION.md (docs)

Modified files:
- SynergyEnvironmentImpl.smali (SharedPreferences check priority)
- MainActivity.smali (first-launch check + onActivityResult)
- AndroidManifest.xml (declare ServerSetupActivity)

Benefits:
- One APK works with any server
- Easy server switching
- Lower barrier to entry for non-technical users

smali_classes2/com/firemint/realracing/ServerSetupActivity$3.smali

@@ -0,0 +1,47 @@
+.class Lcom/firemint/realracing/ServerSetupActivity$3;
+.super Ljava/lang/Object;
+.source "ServerSetupActivity.java"
+
+# interfaces
+.implements Landroid/view/View$OnClickListener;
+
+
+# annotations
+.annotation system Ldalvik/annotation/EnclosingMethod;
+    value = Lcom/firemint/realracing/ServerSetupActivity;->onCreate(Landroid/os/Bundle;)V
+.end annotation
+
+.annotation system Ldalvik/annotation/InnerClass;
+    accessFlags = 0x0
+    name = null
+.end annotation
+
+
+# instance fields
+.field final synthetic this$0:Lcom/firemint/realracing/ServerSetupActivity;
+
+
+# direct methods
+.method constructor <init>(Lcom/firemint/realracing/ServerSetupActivity;)V
+    .locals 0
+
+    .line 55
+    iput-object p1, p0, Lcom/firemint/realracing/ServerSetupActivity$3;->this$0:Lcom/firemint/realracing/ServerSetupActivity;
+
+    invoke-direct {p0}, Ljava/lang/Object;-><init>()V
+
+    return-void
+.end method
+
+
+# virtual methods
+.method public onClick(Landroid/view/View;)V
+    .locals 0
+
+    .line 58
+    iget-object p1, p0, Lcom/firemint/realracing/ServerSetupActivity$3;->this$0:Lcom/firemint/realracing/ServerSetupActivity;
+
+    invoke-static {p1}, Lcom/firemint/realracing/ServerSetupActivity;->access$100(Lcom/firemint/realracing/ServerSetupActivity;)V
+
+    return-void
+.end method