Tracking: framework gaps for porting gis-data-portal — sweep 3 #713

Third sweep of framework gaps for porting gis-data-portal onto SimpleModule, checked against main d42a729c and smpy_modules 594d675. Sweep 2 (#542) is closed: 16 of its 19 fixes cover what the portal needs, and the other 3 continue below.

P1

• file_storage: public sync worker contract to store/open files (+ multipart for server-side puts > 5 GiB) #708 file_storage: a public way for sync workers to store and read files, plus multipart uploads for large server-side writes
• background_tasks: per-task / per-queue opt-out of execution tracking (5 DB writes per task) #710 background_tasks: let individual tasks or queues opt out of execution tracking
• sharing: per-resource-type roles (role → implied actions), incl. a role that may manage shares #707 sharing: per-resource-type roles, including a role that can manage shares
• background_tasks: let resource-policy grants (not just owner/operator) read task status #709 background_tasks: let anyone who passes the resource policy read a task's status (follow-up to background_tasks: progress reporting from tasks and status reads scoped to the task's owner #536)
• billing: pluggable billing subject (per-user on single-tenant hosts), not tenant-only smpy_modules#274 billing: a pluggable billing subject, so billing can be per user (follow-up to smpy_modules#99)

P2

• migrations: framework module data migrations don't reach scaffolded hosts #711 framework module data migrations don't reach scaffolded hosts
• users: host-overridable auth email templates with an HTML part #712 users: host-overridable HTML templates for auth emails

Still deferred: #580 full SSR. The portal's TanStack Start SSR frontend depends on it unless it keeps running as a separate frontend.