Build Excel template download in admin

[raggopaluni]

Description

Admin downloads pre-formatted Excel template.
Champions fill and upload back.

Sheet 1 — Products: Name, Category, Store, Price, Neighbors, Description, Do1-3, Dont1-3, prices per store
Sheet 2 — Services: Business Name, Category, Rating, Reviews, Location, Tag1-3, Price From, Note, Phone

Includes example row and instructions tab.

Acceptance Criteria

• Download button in admin panel
• Opens correctly in Excel and Google Sheets
• Example row included
• Instructions tab included

Dependencies

Issue #6