Slim bottom tab bar to Apple height; remove redundant reload button; bump to 2.4

- Bottom tab bar: reduce vertical padding (8→4), icon size (20→18), and
  bottom inset (8→4) so it matches Apple's standard compact tab bar height
  (Apple Music etc.) instead of a tall bar.
- Remove the manual reload button from the loaded PR toolbar — the detail
  view auto-loads on appearance, so it was redundant clutter. The reload
  button is kept only on the error/retry state. Bump to 2.4.

GiteaPR.xcodeproj/project.pbxproj

@@ -187,7 +187,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 14;
+				CURRENT_PROJECT_VERSION = 15;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = "GiteaPR";
@@ -197,7 +197,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 2.3;
+				MARKETING_VERSION = 2.4;
 				PRODUCT_BUNDLE_IDENTIFIER = com.bueso.giteapr;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;
@@ -211,7 +211,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 14;
+				CURRENT_PROJECT_VERSION = 15;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = "GiteaPR";
@@ -221,7 +221,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 2.3;
+				MARKETING_VERSION = 2.4;
 				PRODUCT_BUNDLE_IDENTIFIER = com.bueso.giteapr;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;