[Design Deliverable] Email spec for Admin Notification for stuck files

[reitermb]

Description: Follows on from #831, delivers spec for sys admin notifications of files stuck in pending / other non-processing states

AC:

• [ ] Internal Raft Review has occurred to ensure DoD standards and QA
• [ ] Dev/Design sync has occurred; resulting tickets created
• [ ] The design is usable and accessible, meaning it adheres to definition of done standards for design work.

  Expand Definition of Done Standards

  - It uses [USWDS components and follows it’s UX guidance](https://designsystem.digital.gov/components/), or a deviation is clearly documented - Language is intentional and [plain](https://plainlanguage.gov/guidelines/); placeholders are clearly documented - It follows [accessibility guidelines](https://accessibility.digital.gov/) and accessibility implementation notes are documented (e.g. clear information hierarchy, color is not the only way meaning is communicated, etc.) - If feedback identifies bigger questions or unknowns, create additional issues to investigate

Tasks:

• [x] Determine the right cadence for the system to check for stuck files
• [ ] Mockup HTML template with the following data: STT, Program Type, Fiscal Period, Section, Submission Date/time

Notes:

• 15 minute threshold was a suggestion from Andrew. ~double the time we'd expect would be required to parse the largest data files

[reitermb]

Stub ticket, related to #2930

[reitermb]

A11y reviewed w/ @ttran-hub and @victoriaatraft on 6/26/2024

[ttran-hub]

Thanks @reitermb @victoriaatraft! As discussed: to help with managing the outstanding pending file, if possible, include the dynamic links to the pending source data files in the Django or STT submission history. The a11y review for the pending email layout template lgtm 🚀.

[robgendron]

Awaiting content feedback and may need some dev input, 1 point remaining.