[feat] Interview evaluation API

[erikbayerlein]

Epic: #71 (Arguição e Entrevista)
Use Case: #66

Fase 2 — Implementação posterior à fase de inscrição.

Description

API for professors to submit interview evaluations for candidates.

Acceptance Criteria

• Professor can create an evaluation for a candidate with 5 aspect ratings (concept enum: FRACO/REGULAR/BOM/OTIMO).
• Each evaluation includes free-text observations field.
• Multiple professors can evaluate the same candidate.
• System calculates per-aspect averages using upper bound of concept (FRACO=4, REGULAR=6, BOM=8, OTIMO=10).
• System calculates overall average across all 5 aspects.
• System determines final concept based on overall average.
• Final concept sets the ceiling for the interview score.
• Evaluator identity (professor) is stored for audit.