chore: upgrade Ruby to 3.4.1 and fix CocoaPods on Blacksmith runners

Blacksmith macOS images ship Ruby 3.4, which removed the 'kconv' stdlib
that xcodeproj 1.27.0 still requires. The Rock Remote Build - iOS job
failed because remote-build-ios.yml never ran ruby/setup-ruby, so it
inherited whatever Ruby the image shipped.

- Bump .ruby-version from 3.3.4 to 3.4.1 (first stable release in the
  3.4 line; upstream 3.4.0 reports as '3.4.0dev' which fails bundler's
  '>= 3.4.0' check)
- Add gem 'nkf' to the Gemfile to replace the removed 'kconv' stdlib
- Raise Gemfile ruby constraint to >= 3.4.1
- Add ruby/setup-ruby step to remote-build-ios.yml so the Rock action
  uses the pinned Ruby instead of the image default
- Regenerate Gemfile.lock under the new toolchain

Made-with: Cursor

Author: roryabraham

.github/workflows/remote-build-ios.yml

@@ -45,6 +45,12 @@ jobs:
         with:
           IS_HYBRID_BUILD: ${{ matrix.is_hybrid_build && 'true' || 'false' }}
 
+      - name: Setup Ruby
+        # v1.229.0
+        uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252
+        with:
+          bundler-cache: true
+
       - name: Checkout specific Mobile-Expensify PR
         if: ${{ matrix.is_hybrid_build && github.event.inputs.mobile_expensify_pr }}
         run: |

.ruby-version

@@ -1 +1 @@
-3.3.4
+3.4.1

Gemfile

@@ -1,7 +1,7 @@
 source "https://rubygems.org"
 
 # You may use http://rbenv.org/ or https://rvm.io/ to install and use this version
-ruby ">= 3.3.4"
+ruby ">= 3.4.1"
 
 gem "cocoapods", "= 1.16.2"
 gem 'activesupport', '>= 7.2.3.1'
@@ -19,3 +19,4 @@ gem 'bigdecimal'
 gem 'logger'
 gem 'benchmark'
 gem 'mutex_m'
+gem 'nkf'

Gemfile.lock

@@ -260,6 +260,7 @@ GEM
     nap (1.1.0)
     naturally (2.3.0)
     netrc (0.11.0)
+    nkf (0.2.0)
     openssl (3.3.1)
     optparse (0.8.1)
     os (1.1.4)
@@ -331,12 +332,13 @@ DEPENDENCIES
   fastlane-plugin-firebase_app_distribution
   logger
   mutex_m
+  nkf
   openssl (>= 3.3.1)
   xcodeproj (~> 1.27)
   xcpretty (~> 0)
 
 RUBY VERSION
-   ruby 3.3.4p94
+   ruby 3.4.1p0
 
 BUNDLED WITH
    2.6.9