SessionType rows exist only via seed — fresh DB blocks session creation & evaluator assignment

[TusharW4ni]

Part of #285 (Group D — robustness).

Problem

SessionType rows exist only because the seed script inserts them. On a fresh/un-seeded database the type table is empty, which blocks session creation (the picker is empty and a type is required) and blocks evaluator assignment (which looks up a "Evaluation Appointment" type and 500s if absent).

Evidence

• prisma/seed.ts — the only source of SessionType rows (~10 types). server/api/session/types.get.ts is a bare findMany; there is no runtime seeding and no UI to create types.
• components/schedule/SessionDetailModal.vue requires a selected type to submit; an empty list makes creation impossible.
• server/api/session/appointments/index.put.ts throws 500 ("seed it before assigning evaluators") when the "Evaluation Appointment" type is missing.

Impact

P1 (environment). A fresh deploy/dev DB without seeding can't create any session or assign any evaluator.

Proposed approach

• Guarantee the required SessionType rows via an idempotent runtime ensure-seed on boot/migration, and/or an ADMIN UI to manage session types.
• At minimum, ensure the "Evaluation Appointment" type always exists before evaluator assignment can be reached.

Acceptance criteria

• A freshly migrated DB (no manual seed) can create sessions and assign evaluators.
• Session types are manageable without editing the seed script (UI or documented ensure-seed).