IOS-2532 Fix Linear comment version diff for hotfix releases

Replace git describe with intelligent tag parsing to ensure hotfix releases correctly diff against the previous version. Previously, hotfix releases would find old tags from merged branches, causing large diffs and notifying many unrelated Linear issues.

Author: ignatovv

fastlane/FastfileDeploy

@@ -99,7 +99,23 @@ platform :ios do
     sh("git push origin refs/tags/#{tag_name} --no-verify --force")
 
     appInfo = settings[:app_info]
-    old_tag_name = sh("git describe --first-parent --tags --abbrev=0 HEAD~").chomp
+
+    # Determine the previous tag to use for diff generation in Linear comments
+    # This ensures hotfix releases (e.g., 0.41.1) correctly diff against the last build
+    # of the previous version (0.41.0/27) instead of finding an old tag from a different branch
+    if build_number.to_i > 1
+      # For incremental builds (e.g., 0.41.0/26 -> 0.41.0/27), use the previous build number
+      old_tag_name = "#{prefix}/#{version}/#{build_number.to_i - 1}"
+    else
+      # For the first build of a new version (e.g., 0.41.1/1), find the last tag of the previous version
+      # Get all tags for the current major version (e.g., all 0.41.x tags), sorted by version
+      all_version_tags = sh("git tag -l '#{prefix}/#{version.split('.')[0]}.*/*' | sort -V").split("\n")
+
+      # Find the index of the current version in the sorted list
+      current_idx = all_version_tags.index { |t| t.start_with?("#{prefix}/#{version}/") }
+      # Use the tag immediately before the current version, or fallback to current tag if not found
+      old_tag_name = current_idx && current_idx > 0 ? all_version_tags[current_idx - 1] : tag_name
+    end
 
     add_linear_comment(
       from_tag: old_tag_name,