feat: add export & share routine feature (#1133)

[prisha-sh]

📌 Description

Implemented the Export & Share Routine feature, allowing users to export routines, share them publicly, and copy routine summaries for easier collaboration and accessibility.

🔗 Related Issue

Closes #1133

🛠 Changes Made

• Added PDF export functionality for routines using jsPDF and html2canvas
• Added copy-to-clipboard support for routine summaries
• Added public routine sharing page and backend endpoint
• Added share link generation and copy link actions
• Enhanced weekly schedule image export with loading and disabled states
• Added user feedback through toast notifications

📸 Screenshots (if applicable)

Add screenshots/GIFs demonstrating:

• Export PDF action
• Copy Summary action
• Public Share Page
• Weekly Schedule Export

✅ Checklist

• Code runs locally
• Followed project structure
• No console errors
• Properly tested changes
• Linked the issue

🚀 Notes for Reviewers

• Public routine viewing is available through a dedicated share route.
• Existing UI patterns and toast notifications were reused to maintain consistency.
• Production build was verified successfully after implementation.

[prisha-sh]

@aryandas2911

Implemented the Export & Share Routine feature and raised a PR.

Added:
• Export routine as PDF
• Download weekly schedule as image
• Copy routine summary
• Public routine sharing

Looking forward to your review. Thanks!