refactor: extract shared vendor category constants

[EmeditWeb]

Problem

The vendor category list is defined in 3 separate files with slightly different values:

• src/pages/Home.tsx (line 207-214): Bootcamps, Online Courses, Universities, Platforms
• src/pages/VendorRegister.tsx (line 11): Bootcamp, OnlineCourse, University, Platform
• src/pages/Vendors.tsx (line 11): same as VendorRegister

The pluralization and naming inconsistencies cause filtering to fail across pages. A vendor registered as "Bootcamp" will not show under "Bootcamps" filter.

Root Cause

The categories list was copied independently into each file during development rather than extracted to a shared constant.

What To Build

1. Create src/constants/categories.ts with the canonical category list
2. Import from the shared constant in all 3 files
3. Ensure consistent naming (pick one convention: Bootcamp or Bootcamps)
4. Update existing vendors in DB to match the canonical names

Files To Touch

• src/constants/categories.ts — new file
• src/pages/Home.tsx — remove local CATEGORIES, import shared
• src/pages/VendorRegister.tsx — remove local CATEGORIES, import shared
• src/pages/Vendors.tsx — remove local CATEGORIES, import shared

Acceptance Criteria

• Categories defined once in src/constants/categories.ts
• All 3 files import from shared constant
• Consistent naming across all pages
• No duplicate category definitions in the codebase

Mandatory Checks

• context/ files read
• npm run build passes
• PR references this issue