Public beta readiness improvements

This release prepares DataNet for a broader public beta with clearer account limits and stronger operational safeguards.

Included

• Refined monthly and annual plan presentation.
• Reliable Stripe webhook processing and account entitlement reconciliation.
• A 30-day payment and cancellation grace period.
• Expanded project, API key, and channel-management workflows.
• Public status, changelog, and tutorial foundations.
• Lifecycle notification coverage for accounts, upgrades, billing issues, and service incidents.

These changes are designed to make both the customer experience and the operational response path easier to understand.