feat: Update subscription payment process - PR approval before payment

[AugustoL]

Description

Update the subscription payment flow described on the Subscriptions page to reflect a new process where PR approval happens before payment, with payments going directly to the DAO.

Current Problem

The current payment process may lead to situations where:

• Users pay for subscriptions that don't meet our criteria
• We need to refund illegitimate subscription payments
• Manual verification happens after payment, creating friction

Proposed New Flow

1. Submit PR First - User submits a Pull Request to the metadata repository with their subscription details (network, token, app, or organization info)
2. PR Review & Approval - OpenScan team reviews the PR to verify legitimacy
3. Payment After Approval - Once PR is approved, user makes payment directly to the DAO
4. PR Merge - After payment confirmation, PR is merged and subscription becomes active

Benefits

• No refunds needed for illegitimate subscriptions
• Clear verification before money changes hands
• Transparent process via GitHub PR
• DAO receives payments directly

Changes Required

• Update Subscriptions page copy to explain new flow
• Add link to metadata repository for PR submission
• Document required PR format/template for each subscription type
• Add DAO payment address/instructions
• Remove or update any existing payment contract integration
• Add step-by-step guide for subscribers

Acceptance Criteria

• Subscriptions page clearly explains the PR-first process
• Links to metadata repo and PR template are provided
• DAO payment details are displayed
• Process is easy to understand for new subscribers