Airdrop: change lock-up proof link to basescan tx

[realproject7]

Problem

The lock-up proof link currently points to https://mint.club/locker/{lockerId}, but Mint Club has no direct page for individual lock-ups. The link leads nowhere useful.

File: src/components/airdrop/CampaignHero.tsx:637-650

Solution

Change the link to point to the basescan transaction instead:

• URL: https://basescan.org/tx/0xb4549d21a3a026d215f38d9bf50779fe337254944ae746d008b3b13cd684adce
• Update config to store LOCKER_TX (tx hash) instead of or alongside LOCKER_ID
• Update the link text to something like "View lock-up proof on Basescan"

Acceptance Criteria

• Lock-up proof link opens the correct basescan transaction page
• Works for both test and prod configs