Status pipeline manager: unify duplicated status config + colors

[hamin2006]

Context

Submission statuses are the backbone of the reviewer table, kanban board, email templates, analytics, and result previews — but they exist as two out-of-sync JSON lists in forms.config with no UI to manage them. Changing the pipeline currently means raw SQL.

Current behavior

• config.application.subfields[status].options drives the table dropdown, status chips w/ counts, board columns, and bulk/assignment flows (12 statuses live on form 19, incl. might_interview, emailed_for_interview, waitlisted).
• config.application.status[] (9 statuses on form 19, {id,label,description}) drives the email-template picker and the Settings result previews.
• The two lists drift independently (form 19 is currently out of sync). No editor for either.
• Chip colors are a hardcoded STATUS_COLORS map in columns.tsx (9 keys); statuses outside it render unstyled. Board fallback pipeline is hardcoded in board/page.tsx.
• config.application.status[*].pageId ("offerPage") has no consumer anywhere.

Desired behavior

• Single admin editor (natural home: Settings or Questions tab) to add/remove/reorder/relabel statuses and assign colors, writing a single source of truth.
• One canonical status list; the reviewer pipeline (subfields options), email-template picker, previews, and analytics derive from it (either unify the JSON shape or auto-sync the two keys on save).
• Colors stored per status in config with a fallback for unconfigured statuses.
• Pipeline order (board columns) follows the configured list order.
• Migration/backfill for existing forms (form 19, 10, …) to the canonical shape.

Acceptance criteria

• UI to add, rename, delete (guarded: in-use), reorder, and color statuses
• Table chips/columns, board, email picker, and previews all reflect one canonical list
• Existing forms migrated; no drift between the two config keys afterward
• Statuses without a configured color get a deterministic fallback color