feat(plugin-webhooks,runtime)!: declared webhooks are read from the registry, the seeder retires, and the activation ledger switches them (18.x step 1, 8b-0g′)

feat(plugin-webhooks,runtime)!: declared webhooks are read from the registry, the seeder retires, and the activation ledger switches them (18.x step 1, 8b-0g′) #20244