Feature/user mgmt

[rsmithlal]

This pull request introduces a new user account settings page and refactors the account update flow to use Turbo Streams for a more modern and interactive experience. It also improves authorization logic for user actions and updates UI components for consistency and clarity.

Account settings and update flow improvements:

• Added a new SettingsController and a settings index view (settings/index.html.erb) with tabbed navigation for platform, personal, account, and privacy settings. The account tab now loads the account edit form via Turbo Frame for a smoother user experience. [1] [2] [3] [4]
• Refactored the user registration controller to support Turbo Stream responses for account updates, including improved error handling and flash messaging. Added strong parameter configuration for account updates and a dedicated path after update. [1] [2] [3]

Authorization and policy updates:

• Updated UserPolicy to restrict access to user management actions based on the manage_platform permission, including index, show, update, and scope resolution. [1] [2] [3]

UI and UX enhancements:

• Replaced the account edit form with a partial that supports Turbo Frames, and improved error display styling. [1] [2] [3]
• Improved flash message handling to support the success type and ensure consistent Bootstrap alert styling.
• Updated the people form to remove redundant labels and hints for a cleaner layout.

Testing and dependencies:

• Added the rspec-rebound gem to the test group in the Gemfile for enhanced RSpec testing capabilities.

Localization:

• Added comprehensive English translations for the new settings page and account edit flow, including tab labels and descriptions. [1] [2]## Summary

Describe the change and the motivation.

Checklist

• Tests added/updated and passing (bin/ci).
• Lint and security checks (rubocop, brakeman, bundler-audit).
• Documentation updated under docs/ describing new/changed functionality.
• Mermaid diagrams (docs/*.mmd) updated to reflect changes.
• Rendered PNGs regenerated with bin/render_diagrams and committed.
• For DB changes, included any needed backfills/dedupes and noted risks.

Screenshots / Diagrams

If applicable, include screenshots or link to updated diagrams.

Notes

Anything reviewers should be aware of (migration order, flags, feature toggles).