feat: create dedicated scanner page for medicine verification system

[S-MOHAMMED-ISMAIL]

Summary

Added a dedicated /scanner page for the upcoming Medicine Verification System.

Closes #2195

---

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

---

Changes Made

• Created a dedicated /scanner route
• Added a scanner placeholder component
• Added a scanner instructions component
• Added a "Coming Soon" indicator for future barcode/QR scanning support
• Implemented responsive layout for desktop and mobile devices
• Followed the existing DevTrack design system and styling

---

How to Test

1. Run the project locally
2. Navigate to /scanner
3. Verify the page title and description are displayed
4. Verify the scanner placeholder card is visible
5. Verify the "Coming Soon" badge is displayed
6. Verify the instructions section is visible
7. Check responsiveness on different screen sizes

---

Screenshots (if UI change)

Added a new Scanner page UI for Medicine Verification.

---

Checklist

• Linked issue in summary
• Self-reviewed the changes
• Verified the page renders correctly
• No new TypeScript errors introduced
• Added/updated tests if applicable

---

Additional Notes

This page serves as the initial entry point for the upcoming Medicine Verification feature and provides a placeholder experience until barcode/QR scanning functionality is implemented.

[vercel]

@S-MOHAMMED-ISMAIL is attempting to deploy a commit to the PRIYANSHU DOSHI's projects Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — please apply the appropriate labels before merging:

Difficulty (pick one):

• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

Quality (optional):

• quality:clean — ×1.2 multiplier
• quality:exceptional — ×1.5 multiplier

Validation (required to score):

• gssoc:approved — counts for points
• gssoc:invalid / gssoc:spam / gssoc:ai-slop — does not score

Type labels (type:*) are auto-detected from files and title. Review and adjust if needed.
Points formula: (difficulty × quality_multiplier) + type_bonus

[S-MOHAMMED-ISMAIL]

The failing Playwright smoke tests appear unrelated to this change.

This PR only adds:

• src/app/scanner/page.tsx
• src/components/scanner/ScannerPlaceholder.tsx
• src/components/scanner/ScannerInstructions.tsx

The failure is occurring in existing E2E tests related to:

• /api/metrics/contributions
• dashboard widgets
• goals
• streak features

Type checks, security checks, and visual regression checks are passing.