Muesli: PR 10.2 - Performance services

[fosterfarrell9]

This PR adds the Step 10.2 backend for Student Performance computation. It

• introduces ComputationService to aggregate assessment points and materialize per-user performance records
• adds Evaluator for rule-based performance checks
• adds background jobs to update records and mark stale certifications
• extends performance records with assessment count fields (total/reviewed/pending/exempt)

[Copilot]

Pull request overview

This PR implements backend services for student performance computation in the Muesli integration. It introduces a computation service to aggregate assessment points, an evaluator for rule-based performance checks, and background jobs to update records and identify stale certifications.

Changes:

• Adds ComputationService to compute and materialize student performance metrics per user
• Adds Evaluator to evaluate performance records against rules (percentage/absolute points, achievements)
• Adds two background jobs: PerformanceRecordUpdateJob for computing records and CertificationStaleCheckJob for detecting outdated certifications
• Extends performance records with assessment count fields (total, reviewed, pending, exempt)
• Adds .stale scope to Certification model to identify certifications older than their corresponding records

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
app/models/student_performance/computation_service.rb	Service to aggregate points and assessment counts, materialize performance records via upsert
app/models/student_performance/evaluator.rb	Evaluates performance records against rules, returns pass/fail proposals with details
app/workers/performance_record_update_job.rb	Sidekiq job to compute records for one user or all lecture members
app/workers/certification_stale_check_job.rb	Recomputes records and logs stale certifications
app/models/student_performance/certification.rb	Adds .stale scope using SQL join to find certifications older than records
db/migrate/20260226000001_add_assessment_counts_to_performance_records.rb	Adds four integer count fields to performance records table
db/schema.rb	Schema version update reflecting new columns
spec/factories/student_performance_records.rb	Updates factory with default values for new count fields
spec/models/student_performance/computation_service_spec.rb	Comprehensive tests for aggregation, upserts, counts, exempt/pending logic
spec/models/student_performance/evaluator_spec.rb	Tests for percentage/absolute/achievement rules, bulk evaluation
spec/workers/performance_record_update_job_spec.rb	Tests for single-user and full-lecture computation
spec/workers/certification_stale_check_job_spec.rb	Tests for staleness detection and logging
spec/models/student_performance/certification_spec.rb	Tests for .stale scope edge cases