[Docs] Update /docs/admin-guide for Sprint 3a + ClickUp transition status

[ProfessorPolymorphic]

Context

Sprint 4 audit (post-PR #93) found that app/docs/admin-guide/page.tsx (144 LOC) predates Sprint 3a delivery improvements and doesn't acknowledge the in-progress ClickUp transition.

Gaps to close

Sprint 3a additions missing:

• The named-human intake flow (Colin Armitage as the named owner; SLA captured in lib/intake-config.ts).
• The /intake/[token] submitter status URL — bookmarkable, no login required.
• The similarity preview that runs during the assessment (POST /api/similarity/preview), not just on the post-submit admin view.

ClickUp transition framing:

• The current admin-guide describes a steady-state Postgres-backed workflow without flagging that /admin/submissions is transitional. Per CLAUDE.md and REFACTOR.md, Sprint 3b (ClickUp wiring) will retire /admin/submissions once landed; the doc should at minimum mention this so admins don't invest in workflows that will move.

Acceptance criteria

• Submission lifecycle described accurately, including the new /intake/[token] status surface
• Named-human + SLA flow documented
• Similarity preview (during-assessment) called out separately from the post-submit similarity panel
• Brief callout on the in-progress ClickUp transition and what's expected to change
• Submission status values verified against current Postgres schema

[ProfessorPolymorphic]

Closed by #321.

The page listed a six-state lifecycle that ADR 0001 superseded; it now carries the real twelve-state ladder, plus a section on where the admin surfaces actually sit — registry edits are overwritten by the next seed:portfolio TRUNCATE, status narrative comes from ClickUp, requests live in tech_requests, and submissions review is the part that's still the live workflow.

One thing surfaced while doing this that is not fixed: STATUS_OPTIONS in app/admin/registry/[id]/page.tsx still offers the legacy submission states and the pre-ADR-0001 capitalised union. applications.status has no CHECK constraint, so those write successfully and publicStageFromStatus() buckets them as Exploring — an admin can silently misfile a project on /portfolio, and verify:portfolio won't catch it because it reads lib/portfolio.ts, not the database. The page warns against using that control for now. Worth its own issue; the fix is a product decision (restrict the list / add a DB check / extend the verifier / retire the surface).