Store school email domains

[PetarSimonovic]

Status

Closes #1325

What's changed?

• Add a school_email_domains table
• Add a SchoolEmailDomain model
• Perform minimal formatting on a domain to strip leading @ and lowercase the string
• Update association on School
• Add and update specs

[Copilot]

Pull request overview

Introduces first-class storage for school email domains by adding a dedicated table/model and wiring it into the School domain model, with accompanying specs.

Changes:

• Added school_email_domains table with a composite unique index per school.
• Added SchoolEmailDomain model with before_validation normalization (strip leading @, downcase).
• Updated School to has_many :school_email_domains and added/updated model specs.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
spec/models/school_spec.rb	Adds association + dependent-destroy coverage for school_email_domains.
spec/models/school_email_domain_spec.rb	Adds model spec coverage for domain normalization behavior.
db/schema.rb	Reflects new school_email_domains table and foreign key.
db/migrate/20260420104937_create_school_email_domains.rb	Creates the new school_email_domains table and composite unique index.
app/models/school_email_domain.rb	Introduces the new model and domain normalization callback.
app/models/school.rb	Adds has_many :school_email_domains, dependent: :destroy.

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[github-actions]

Test coverage

89.5% line coverage reported by SimpleCov.
Run: https://github.com/RaspberryPiFoundation/editor-api/actions/runs/24773204189

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

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[fspeirs]

Overall this looks like the right approach. I have one consideration about validating domains - I feel like it would be helpful to be stricter in checking that the user hasn't typo'ed their domain or misunderstood what we are asking for.