[TheGreatAxios]

Summary

• Mount @corbits/cron (CL-8183): its own Hono<TenantEnv> at /, requireTenantMember reading the tenant middleware's context the same way the mailbox mount's resolvePrincipal does, applyCronMigrations run at boot next to runArtifactMigrations, and a createCronTicker started at 60s intervals whose deliver builds an RFC 5322 frame with @corbits/mailbox's own buildMailFrame/generateMailboxMessageId and sends it through the same lookups.persistMail every other outbound frame in this hub already dispatches through. Sender address is cron@<tenant domain>, resolved the same way the mailbox mount's senderAddressFor does. The ticker stops in close().
• Re-pin @corbits/memory to e74da20f148a302dff5400915fe504ee2395e913 (0.1.3, adds tenant/principal FKs) in apps/hub/package.json, with bun.lock updated to match.
• applyCronMigrations/cronMigrations weren't exported from packages/cron's barrel — added them.

Test plan

• bun run typecheck
• bun run lint
• bun run fmt
• bun test in apps/hub (63 pass, DB-gated suites skip without DATABASE_URL, as expected locally)
• HUB_DATA_DIR=$(mktemp -d) bun apps/hub/src/index.ts with no DATABASE_URL fails on config validation, not on import
• Note: bun run check's scripts/ci-jobs.test.ts fails on this branch, but it also fails against a clean origin/main checkout — pre-existing drift between that test and .github/workflows/ci.yml, untouched by this change.

[linear-code]

CL-8183