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/CommunityServerManager.smali

@@ -0,0 +1,183 @@
+.class public Lcom/firemint/realracing/CommunityServerManager;
+.super Ljava/lang/Object;
+.source "CommunityServerManager.java"
+
+
+# static fields
+.field private static final PREFS_NAME:Ljava/lang/String; = "rr3_community_server"
+
+.field private static final KEY_SERVER_URL:Ljava/lang/String; = "server_url"
+
+.field private static final TAG:Ljava/lang/String; = "CommunityServerManager"
+
+
+# direct methods
+.method public constructor <init>()V
+    .locals 0
+
+    .line 8
+    invoke-direct {p0}, Ljava/lang/Object;-><init>()V
+
+    return-void
+.end method
+
+.method public static checkServerUrl(Landroid/content/Context;)Z
+    .locals 3
+
+    const-string v0, "rr3_community_server"
+
+    const/4 v1, 0x0
+
+    .line 16
+    invoke-virtual {p0, v0, v1}, Landroid/content/Context;->getSharedPreferences(Ljava/lang/String;I)Landroid/content/SharedPreferences;
+
+    move-result-object p0
+
+    const-string v0, "server_url"
+
+    const/4 v2, 0x0
+
+    .line 17
+    invoke-interface {p0, v0, v2}, Landroid/content/SharedPreferences;->getString(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
+
+    move-result-object p0
+
+    if-eqz p0, :cond_0
+
+    .line 20
+    invoke-virtual {p0}, Ljava/lang/String;->isEmpty()Z
+
+    move-result p0
+
+    if-nez p0, :cond_0
+
+    const/4 v1, 0x1
+
+    :cond_0
+    return v1
+.end method
+
+.method public static clearServerUrl(Landroid/content/Context;)V
+    .locals 2
+
+    const-string v0, "rr3_community_server"
+
+    const/4 v1, 0x0
+
+    .line 56
+    invoke-virtual {p0, v0, v1}, Landroid/content/Context;->getSharedPreferences(Ljava/lang/String;I)Landroid/content/SharedPreferences;
+
+    move-result-object p0
+
+    .line 57
+    invoke-interface {p0}, Landroid/content/SharedPreferences;->edit()Landroid/content/SharedPreferences$Editor;
+
+    move-result-object p0
+
+    const-string v0, "server_url"
+
+    .line 58
+    invoke-interface {p0, v0}, Landroid/content/SharedPreferences$Editor;->remove(Ljava/lang/String;)Landroid/content/SharedPreferences$Editor;
+
+    .line 59
+    invoke-interface {p0}, Landroid/content/SharedPreferences$Editor;->apply()V
+
+    const-string p0, "CommunityServerManager"
+
+    const-string v0, "\u274c Server URL cleared"
+
+    .line 61
+    invoke-static {p0, v0}, Landroid/util/Log;->i(Ljava/lang/String;Ljava/lang/String;)I
+
+    return-void
+.end method
+
+.method public static getServerUrl(Landroid/content/Context;)Ljava/lang/String;
+    .locals 3
+
+    const-string v0, "rr3_community_server"
+
+    const/4 v1, 0x0
+
+    .line 28
+    invoke-virtual {p0, v0, v1}, Landroid/content/Context;->getSharedPreferences(Ljava/lang/String;I)Landroid/content/SharedPreferences;
+
+    move-result-object p0
+
+    const-string v0, "server_url"
+
+    const-string v1, ""
+
+    .line 29
+    invoke-interface {p0, v0, v1}, Landroid/content/SharedPreferences;->getString(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
+
+    move-result-object p0
+
+    .line 31
+    new-instance v0, Ljava/lang/StringBuilder;
+
+    invoke-direct {v0}, Ljava/lang/StringBuilder;-><init>()V
+
+    const-string v1, "\ud83d\udd17 Getting server URL: "
+
+    invoke-virtual {v0, v1}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+
+    invoke-virtual {v0, p0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+
+    invoke-virtual {v0}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;
+
+    move-result-object v0
+
+    const-string v1, "CommunityServerManager"
+
+    invoke-static {v1, v0}, Landroid/util/Log;->i(Ljava/lang/String;Ljava/lang/String;)I
+
+    return-object p0
+.end method
+
+.method public static saveServerUrl(Landroid/content/Context;Ljava/lang/String;)V
+    .locals 2
+
+    const-string v0, "rr3_community_server"
+
+    const/4 v1, 0x0
+
+    .line 41
+    invoke-virtual {p0, v0, v1}, Landroid/content/Context;->getSharedPreferences(Ljava/lang/String;I)Landroid/content/SharedPreferences;
+
+    move-result-object p0
+
+    .line 42
+    invoke-interface {p0}, Landroid/content/SharedPreferences;->edit()Landroid/content/SharedPreferences$Editor;
+
+    move-result-object p0
+
+    const-string v0, "server_url"
+
+    .line 43
+    invoke-interface {p0, v0, p1}, Landroid/content/SharedPreferences$Editor;->putString(Ljava/lang/String;Ljava/lang/String;)Landroid/content/SharedPreferences$Editor;
+
+    .line 44
+    invoke-interface {p0}, Landroid/content/SharedPreferences$Editor;->apply()V
+
+    .line 46
+    new-instance p0, Ljava/lang/StringBuilder;
+
+    invoke-direct {p0}, Ljava/lang/StringBuilder;-><init>()V
+
+    const-string v0, "\u2705 Server URL saved: "
+
+    invoke-virtual {p0, v0}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+
+    invoke-virtual {p0, p1}, Ljava/lang/StringBuilder;->append(Ljava/lang/String;)Ljava/lang/StringBuilder;
+
+    invoke-virtual {p0}, Ljava/lang/StringBuilder;->toString()Ljava/lang/String;
+
+    move-result-object p0
+
+    const-string p1, "CommunityServerManager"
+
+    invoke-static {p1, p0}, Landroid/util/Log;->i(Ljava/lang/String;Ljava/lang/String;)I
+
+    return-void
+.end method