Teacher model: subjects, role, priority weight (schema + onboarding)

[guangshinhaha]

Context

Prerequisite for the Stars half of the auto-assignment algorithm. Today prisma/schema.prisma only stores teacher type (REGULAR / PERMANENT_RELIEF) — no subjects, no role, no priority. Without this, "compatibility matching" can't happen.

Scope

• Schema additions to `Teacher`:
  • `subjects: String[]` (or normalised `TeacherSubject` join table if we want filtering)
  • `role: TeacherRole` enum — `SRE | UNTRAINED | FAJT | EO | REGULAR` (extend as schools require)
  • `priorityWeight: Int?` (manual override)
• Onboarding wizard step: capture role + subjects when bulk-importing the teacher whitelist (CSV column or per-row UI).
• Teacher edit page surfaces these fields.
• aSc XML importer populates subjects where the XML provides them.

Acceptance criteria

• Migration ships without data loss.
• New teachers created via onboarding have role/subjects set.
• Existing teachers default to `REGULAR` and empty subjects (admin can backfill).
• Schema is consumed by the auto-assign algorithm ticket.

Refs

• docs/research/competitive-gap-analysis.md §4 item 1 (prereq)
• Westwood's role taxonomy (§2)

[guangshinhaha]

Closed by PR #14 — SchoolRole model, role management, subject derivation