Use bundle exec for rake in CLAUDE.md commands (#785)

Before, some listed commands called rake directly which resulted in
conflicting gem version output because rake tries to use the system
RubyGems environment eg.

```
❯ rake standard
WARN: Unresolved or ambiguous specs during Gem::Specification.reset:
      json (~> 2.3)
      Available/installed versions of this gem:
      - 2.19.3
      - 2.18.0
      prism (~> 1.7)
      Available/installed versions of this gem:
      - 1.9.0
      - 1.8.1
WARN: Clearing out unresolved specs. Try 'gem cleanup <gem>'
Please report a bug if this causes problems.
```

Now, we specify bundle exec for the rake commands to use the bundled
versions.

Author: jaredlt

rails/ai-rules/CLAUDE.md

@@ -24,8 +24,8 @@ bundle exec rspec spec/models         # Model specs only
 bundle exec rspec spec/requests       # Request specs only
 bundle exec rspec spec/path/to/file_spec.rb  # Run all tests in file
 bundle exec rspec spec/path/to/file_spec.rb:72  # Run just the test at line 72
-rake standard                         # Lint
-rake standard:fix                     # Auto-fix lint issues
+bundle exec rake standard             # Lint
+bundle exec rake standard:fix         # Auto-fix lint issues
 bin/rails db:migrate                  # Run migrations
 bin/rails suspenders:db:migrate       # Migrate + annotate
 bin/rails suspenders:cleanup:organize_gemfile  # Sort Gemfile