DC-472(Bug): Show correct offboarding screen for co-loaded users

[noxmwalsh]

Jira ticket

DC-472

Description

This PR resolves off-boarding reason from the warehouse household cohort as opposed to the session flag from before:

• Adds CoLoadedCohortClassifier (shared with dashboard household reads) to classify households as CoLoadedOnly vs mixed/applicant
• SubmitIdProofingCommandHandler: on failure paths (SNAP/TANF mismatch, no ID, Socure failure, max attempts), looks up household by email and returns coLoadedOnly when the cohort is co-loaded-only
• ProcessWebhookCommandHandler: on DocV rejection, same cohort lookup; co-loaded-only users get coLoadedOnly instead of docVerificationFailed
• Frontend: off-boarding page treats reason=coLoadedOnly like co-loaded session; analytics maps it to not_found
• Seeds: co-loaded-pending-id-proofing persona seeded with IsCoLoaded = false so local testing matches production

Non-co-loaded / mixed households are unchanged: they still get idProofingFailed or docVerificationFailed and the generic screens.

Links to related PRs

None

Completion tasks

• Added relevant tests
  • CoLoadedCohortClassifierTests
  • SubmitIdProofingCommandHandlerTests (SNAP mismatch + no-ID -> coLoadedOnly)
  • ProcessWebhookCommandHandlerTests (DocV reject + co-loaded-only -> coLoadedOnly)
  • off-boarding/page.test.tsx (reason=coLoadedOnly shows co-loaded copy)
  • DatabaseSeederTests (pending persona expects IsCoLoaded = false)
• Meets acceptance criteria in ticket
• Configuration changes: none (no new env vars, secrets, or appsettings)

Test plan

Flow	Steps	Expected
Co-loaded-only SNAP fail	OTP login, ID proofing, DOB 03/05/1984 + wrong SNAP	/off-boarding?reason=coLoadedOnly, co-loaded heading
Co-loaded-only DocV reject	Reach DocV pending, Socure REJECT webhook	Same co-loaded screen
Non-co-loaded SNAP fail	sebt.dc+non-co-loaded@codeforamerica.org, DOB 10/09/1986 + wrong SNAP	?reason=idProofingFailed, "We want to keep your account safe"
Non-co-loaded DocV reject	DocV pending, REJECT webhook	?reason=docVerificationFailed, "We couldn't verify your identity"