feat: Implement Accept-Language middleware and German translations

[kevalyq]

Summary

Implements Accept-Language header detection middleware and adds German translations for password reset emails.

Changes

Middleware Implementation

• ✅ Created SetLocaleFromHeader middleware to automatically detect and set locale from HTTP Accept-Language header
• ✅ Registered middleware in API group to apply to all API routes
• ✅ Support for English (en) and German (de) locales with fallback to configured default
• ✅ Handles quality values in Accept-Language header (e.g., de-DE,de;q=0.9,en;q=0.8)
• ✅ Type-safe fallback handling for PHPStan Level Max compliance

Translations

• ✅ Translated password reset email template to German
• ✅ Created JSON-based translation file (lang/de.json) with 11 translated strings
• ✅ Used Laravel's __() helper for all user-facing strings in email template
• ✅ Parameter replacement support (e.g., :minutes placeholder)

Testing

• ✅ 7 comprehensive PEST tests for middleware functionality
• ✅ 5 comprehensive PEST tests for email localization
• ✅ All 152 tests passing (446 assertions)

Quality Assurance

• ✅ PHPStan Level Max: No errors
• ✅ Laravel Pint: Code style compliant
• ✅ REUSE 3.3: License compliance verified
• ✅ CHANGELOG updated

Testing

# Run all tests
ddev exec vendor/bin/pest

# Test middleware specifically
ddev exec vendor/bin/pest tests/Feature/LocaleMiddlewareTest.php

# Test translations
ddev exec vendor/bin/pest tests/Feature/PasswordResetEmailLocalizationTest.php

Example Usage

API Request with Accept-Language header

curl -H "Accept-Language: de" https://api.secpal.com/api/health
# Locale will be set to 'de' for this request

Password Reset Email

When a German-speaking user requests password reset:

• Subject: "Passwort zurücksetzen"
• Body: "Hallo {name}, Sie haben eine Passwort-Zurücksetzung für Ihr SecPal-Konto angefordert..."

Related Issues

Part of: #83
Fixes: #87

Checklist

• Code follows project coding standards (Pint, PHPStan Level Max)
• All tests pass (152 tests, 446 assertions)
• CHANGELOG.md updated
• REUSE 3.3 compliant (copyright headers added)
• Commit messages follow conventional commits
• PR size < 600 LOC

[github-actions]

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[Copilot]

Pull Request Overview

This PR adds internationalization (i18n) support for password reset emails, enabling German translations alongside English. The implementation includes locale detection via HTTP Accept-Language headers and comprehensive test coverage for both translation functionality and middleware behavior.

• Introduces SetLocaleFromHeader middleware to automatically detect and set application locale based on Accept-Language HTTP headers
• Adds German translations for all password reset email strings in lang/de.json
• Updates password reset email template to use Laravel's __() translation helper

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
app/Http/Middleware/SetLocaleFromHeader.php	New middleware to parse Accept-Language header and set application locale with fallback to configured default
bootstrap/app.php	Registers SetLocaleFromHeader middleware to API route group
resources/views/emails/password-reset.blade.php	Wraps all user-facing strings with __() helper for translation support
lang/de.json	German translations for all password reset email strings
lang/de.json.license	License header for German translation file
lang/.translation_io	Translation.io timestamp metadata
lang/.translation_io.license	License header for translation metadata
tests/Feature/PasswordResetEmailLocalizationTest.php	5 tests verifying translation strings exist and work correctly in both English and German
tests/Feature/LocaleMiddlewareTest.php	7 tests validating middleware locale detection, header parsing, and fallback behavior
CHANGELOG.md	Documents new i18n features and test additions

[github-actions]

💡 Tip: Consider Using Draft PRs

Benefits of opening PRs as drafts initially:

• 💰 Saves CI runtime and Copilot review credits
• 🎯 Automatically sets linked issues to "🚧 In Progress" status
• 🚀 Mark "Ready for review" when done to trigger full CI pipeline

How to convert:

1. Click "Still in progress? Convert to draft" in the sidebar, OR
2. Use gh pr ready when ready for review

This is just a friendly reminder - feel free to continue as is! 😊