List the explorer in Safe{Wallet}'s public Safe Apps

[rickstaa]

Once #816 is live, Safe users can add the explorer as a custom Safe App. Listing it in Safe{Wallet}'s public app catalogue would let them find it without a custom URL or Safe's "not in the default Safe Apps list" warning.

Blocked: Safe has paused new Safe App listings while it reworks the submission process.

The explorer already meets the technical requirements (manifest, CORS header, auto-connect inside Safe). When listings reopen:

• Submit Safe's listing request form.
• Agree commercial terms with Safe (listing fee, revenue share, launch support).
• Provide the repo link and a short test plan for Safe's QA review.