Graceful downgrade to free plan

We replaced the binary “subscription cancelled” state with a graceful downgrade path that keeps customers on a free plan with read-only access while their card situation is sorted out.

• Implemented graceful switch to a free plan when a paid subscription ends, instead of hard-disabling the workspace.
• Added handling for organizations that already had multiple historical free-plan rows so the new state lands cleanly.
• Wired asset-deletion windows into the downgrade so videos beyond the free quota are removed on a defined schedule rather than immediately.