feat: add Invoice management feature with full CRUD

[devin-ai-integration]

Summary

Adds a complete Invoice management feature with full CRUD operations on both the Spring Boot backend and Angular frontend, following JHipster conventions.

Backend

• Invoice JPA entity with fields: number (String), date (LocalDate), dueDate (LocalDate), amount (BigDecimal), status (InvoiceStatus enum), and a Many-to-One relationship to BankAccount
• InvoiceStatus enum: DRAFT, SENT, PAID, OVERDUE
• InvoiceRepository with eager loading for the bankAccount relationship
• InvoiceResource REST controller with endpoints: POST, PUT, PATCH, GET (list), GET (single), DELETE at /api/invoices
• Liquibase migrations for table creation and foreign key constraint
• Ehcache configuration for the Invoice entity
• Fake data CSV with 10 sample invoices

Frontend

• List view with sortable columns for all fields
• Detail view showing all invoice properties
• Create/Edit form with reactive form validation and bank account dropdown
• Delete confirmation dialog
• Routing with lazy loading and resolve guards
• i18n translations for all labels and enum values
• Navbar menu item under Entities

Tests

• InvoiceResourceIT - Full integration test covering create, read, update (PUT/PATCH), delete, validation (required fields), and error cases (ID mismatch, non-existing)
• InvoiceTest - Domain model equals/hashCode verification and relationship test
• InvoiceAsserts / InvoiceTestSamples - Test helpers
• Angular Vitest specs for all components: service, list, detail, update, delete dialog, form service, routing resolve

Review & Testing Checklist for Human

• Verify the Invoice list page loads correctly at /invoice and displays sortable columns
• Test creating a new invoice with all required fields and linking to a bank account
• Test editing an existing invoice and verify changes persist
• Test deleting an invoice via the delete confirmation dialog
• Verify the Invoice detail view displays all fields including the linked bank account
• Check that form validation enforces required fields (number, date, dueDate, amount, status)

Notes

• Follows the same patterns as the existing BankAccount entity for consistency
• The Invoice entity uses LAZY fetch for the bankAccount relationship with eager loading queries in the repository
• All JHipster needle comments are preserved for future entity generation

Link to Devin session: https://partner-workshops.devinenterprise.com/sessions/10d61b7f4a4346bb98b28ca397e75cf4

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[devin-ai-integration]

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 6 additional findings.