[Core]: Fix EmailTemplateType enum — document types, not field types #667

Modules/Core/Enums/EmailTemplateType.php currently declares TEXT/NUMBER/DATE/BOOLEAN with labels like "Single Line Text" and "Date Picker" — custom-field types pasted into the email-template enum. The intended domain (//'invoice', 'quote', 'payment', 'reminder') survives only as a comment. Every consumer that must filter templates by document type (#164 quote templates, #400 auto-send, #480 reminders, status-aware selection) is blocked; today InvoiceService::resolveEmailDefaults() works around it by matching on the magic title invoice_sent.

v1 spec: email_template_type column with values invoice/quote, filtered in application/modules/mailer/controllers/Mailer.php:83,141.

Specific

• Enum cases become INVOICE='invoice', QUOTE='quote', PAYMENT='payment', REMINDER='reminder' with sensible labels/colors.
• Data migration maps existing rows: seeded titles invoice_sent→invoice, quote_sent→quote, payment_received→payment, user_invitation→ nullable/system (decide: add SYSTEM case or leave type nullable).
• EmailTemplateForm type select and EmailTemplatesTable badge use the new cases.
• InvoiceService::resolveEmailDefaults() filters type = INVOICE (keeping title fallback for back-compat this release).

Measurable

No code path references TEXT/NUMBER/DATE/BOOLEAN on email templates; template pickers list only same-type templates.

Achievable

Enum + migration + two Filament touch points + one service filter; EmailTemplateFactory/seeder updated in the same PR (factory-schema contract).

Relevant

Prerequisite for the entire typed-template roadmap (#164, #400, #480, #235/#239/#230).

Time-Bound

Small; schedule before #164.

Arrange

Seeded templates for one company; an invoice for that company.

Act

Run migration; open EmailTemplateForm; call resolveEmailDefaults().

Assert

• email_templates.type values are in invoice|quote|payment|reminder (or null) after migration
• Type select shows the four document types
• resolveEmailDefaults() picks the invoice-typed template without relying on the title
• EmailTemplateFactory produces valid typed rows (suite green)