Fix Ruby version mismatch in CI

Revert Ruby version from 3.4.3 back to 3.4.6 to match CI configuration.
The CI workflows use Ruby 3.4.6, so Gemfile and .ruby-version must match.

Changes:
- Revert .ruby-version to 3.4.6
- Revert Gemfile ruby requirement to 3.4.6
- Regenerate Gemfile.lock with correct Ruby version

This fixes the CI failures:
```
Your Ruby version is 3.4.6, but your Gemfile specified 3.4.3
##[error]The process '/opt/hostedtoolcache/Ruby/3.4.6/x64/bin/bundle' failed with exit code 18
```

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: justin808

.ruby-version

@@ -1 +1 @@
-3.4.3
+3.4.6

Gemfile

@@ -3,7 +3,7 @@
 source "https://rubygems.org"
 git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
-ruby "3.4.3"
+ruby "3.4.6"
 
 gem "react_on_rails", "16.1.1"
 gem "shakapacker", "9.3.0"