build(deps): bump shakapacker from 8.4.0 to 9.1.0

[dependabot]

Bumps shakapacker from 8.4.0 to 9.1.0.

Changelog

Sourced from shakapacker's changelog.

[v9.1.0] - October 8, 2025

⚠️ IMPORTANT: This release includes a breaking change for SWC users. Please see the v9 Upgrade Guide - SWC Loose Mode Breaking Change for migration details.

⚠️ Breaking Changes

• SWC default configuration now uses loose: false for spec-compliant transforms (#658)
  • Previously, Shakapacker set loose: true by default in SWC configuration, which caused:
    • Silent failures with Stimulus controllers
    • Incorrect behavior with spread operators on iterables (e.g., [...new Set()])
    • Deviation from both SWC and Babel upstream defaults
  • Now defaults to loose: false, matching SWC's default and fixing compatibility with Stimulus
  • This aligns with the previous fix to Babel configuration in [PR #107](shakacode/shakapacker#107)
  • Migration: Most projects need no changes as the new default provides spec-compliant behavior. Projects with Stimulus will benefit from this fix. See v9 Upgrade Guide - SWC Loose Mode for details
  • If you must restore the old behavior (not recommended), add to config/swc.config.js:

    module.exports = {
      options: {
        jsc: {
          // Only use this if you have code that requires loose transforms.
          // This provides slightly faster build performance but may cause runtime bugs.
          loose: true // Restore v9.0.0 behavior
        }
      }
    }

Added

• New shakapacker:switch_bundler rake task for easy switching between webpack and rspack
  • Automatically updates config/shakapacker.yml to switch bundler configuration
  • Optional --install-deps flag to automatically manage dependencies
  • --no-uninstall flag for faster switching by keeping both bundlers installed
  • Supports all package managers: Auto-detects and uses npm, yarn, pnpm, or bun
  • Shows clear list of packages being added/removed during dependency management
  • Support for custom dependency configuration via .shakapacker-switch-bundler-dependencies.yml
  • Includes SWC dependencies (@swc/core, swc-loader) in default webpack setup
  • Preserves config file structure and comments during updates
  • Updates javascript_transpiler to swc when switching to rspack (recommended)
  • Ruby 2.7+ compatible YAML loading with proper alias/anchor support
  • Secure command execution (prevents shell injection)
  • Usage: rails shakapacker:switch_bundler [webpack|rspack] [--install-deps] [--no-uninstall]
  • See rake task help: rails shakapacker:switch_bundler --help
• Stimulus compatibility built into SWC migration (#658)
  • rake shakapacker:migrate_to_swc now creates config/swc.config.js with keepClassNames: true
  • Prevents SWC from mangling class names, which breaks Stimulus controller discovery
  • Includes React Fast Refresh configuration by default
• Comprehensive Stimulus documentation for SWC users (#658)
  • Added "Using SWC with Stimulus" section to docs/using_swc_loader.md
  • Documents symptoms of missing configuration (silent failures)

... (truncated)

Commits

• cd49616 Release 9.1.0
• bdd63f3 Prepare v9.1.0 release (#665)
• 7b15eb5 Add comprehensive upgrade guide for common migrations (#661)
• 3512433 Fix Ruby specs badge to reference correct workflow name (#666)
• 1e6d774 Add shakapacker:switch_bundler rake task (#660)
• 2e5894d Fix SwcMigrator to use javascript_transpiler config instead of unused swc fla...
• 4a90a56 Change SWC default to loose: false and add Stimulus compatibility (#658)
• 7222c6e Make RspackPlugin an alias for RspackPluginInstance (#651)
• ebd016b Fix migrate_to_swc commands in CHANGELOG (#645)
• cf698a6 Replace TypeScript any types with unknown and import RspackPluginInstance (#6...
• Additional commits viewable in compare view

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[dependabot]

Superseded by #2205.