Restructure PR detail: remove Commits tab, bottom icon tab bar, toolbar actions, markdown overview; bump to 1.9

- Remove the Commits tab (not useful).
- Move the section switcher to a bottom tab bar with icons (Overview /
  Conversation / Files / Checks) instead of a top segmented control.
- Move Review (menu) and Merge into the navigation toolbar, removing the
  bottom action bar.
- Add an Overview tab that renders the PR body as markdown via SwiftUI's
  built-in AttributedString(markdown:) (no third-party dependency).
- Bump to 1.9.

GiteaPR.xcodeproj/project.pbxproj

@@ -187,7 +187,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 9;
+				CURRENT_PROJECT_VERSION = 10;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = "GiteaPR";
@@ -197,7 +197,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 1.8;
+				MARKETING_VERSION = 1.9;
 				PRODUCT_BUNDLE_IDENTIFIER = com.bueso.giteapr;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;
@@ -211,7 +211,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 9;
+				CURRENT_PROJECT_VERSION = 10;
 				DEVELOPMENT_TEAM = "";
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_KEY_CFBundleDisplayName = "GiteaPR";
@@ -221,7 +221,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 1.8;
+				MARKETING_VERSION = 1.9;
 				PRODUCT_BUNDLE_IDENTIFIER = com.bueso.giteapr;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_EMIT_LOC_STRINGS = YES;