Change Review, guided onboarding & safer deletes

✨ New Features

• Added onboarding dialogs that walk you through GitLaw the first time you sign in.
• Added a clipboard export so you can copy content out of GitLaw into Word, Google Docs, or email with formatting preserved.

🔧 Improvements

• Improved the change-review experience — comparing versions and accepting or rejecting suggested edits is now clearer and more reliable.
• Improved document loading during AI edits so drafts update more smoothly as the agent works.
• Added a two-step confirmation before deleting an organisation to prevent accidental loss.
• Refreshed the marketing site with new landing pages.

🐞 Fixes

• Fixed layout issues in the document canvas and change-review view.
• Fixed the onboarding layout on mobile.