feat: Translate ui

[alex289]

Type of change

• 🐛 Bug fix
• 🚀 New feature
• ❓ Other (please specify)

Description

• Translate whole ui
• Add lang switcher

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[Copilot]

Pull request overview

This PR introduces UI internationalization across the frontend using Paraglide message functions, and adds a language switcher to let users change the interface language.

Changes:

• Replaced hardcoded UI strings (labels, toasts, aria labels, empty states) with Paraglide m.*() messages across routes and shared components.
• Added app-level i18n bootstrap (initializeI18n) and locale persistence/configuration (including Zod locale configuration).
• Added a language selector in Profile settings to switch locales.

Reviewed changes

Copilot reviewed 43 out of 43 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
frontend/src/routes/login.tsx	Localize image alt/title text on login page.
frontend/src/routes/_authenticated/settings/security.tsx	Localize security page head/meta, validation messages, labels, and toasts.
frontend/src/routes/_authenticated/settings/profile.tsx	Localize profile page + add language switcher and locale change handler.
frontend/src/routes/_authenticated/settings.tsx	Localize settings layout/sidebar labels and page titles.
frontend/src/routes/_authenticated/repositories/index.tsx	Localize repositories page head and loading/description text.
frontend/src/routes/_authenticated/applications/index.tsx	Localize applications page head, stats, search/empty state text, and menu labels.
frontend/src/routes/_authenticated/applications/$id.index.tsx	Localize application details UI, toasts, and labels; improve commit display handling.
frontend/src/routes/_authenticated/agents/index.tsx	Localize agents page head and loading/description text.
frontend/src/routes/_authenticated/admin/users.tsx	Localize admin users page head and content strings.
frontend/src/routes/_authenticated/admin/system-info.tsx	Localize system info page head and content strings.
frontend/src/routes/_authenticated/admin/oidc-providers.tsx	Localize OIDC providers page head, content, and action labels.
frontend/src/routes/_authenticated/admin.tsx	Localize admin layout/sidebar labels and page titles.
frontend/src/main.tsx	Add i18n initialization bootstrap and localize router fallback UI.
frontend/src/lib/i18n.ts	Add locale initialization, persistence, and Zod locale loading/config.
frontend/src/components/ui/sidebar.tsx	Localize sidebar accessibility labels and mobile sheet text.
frontend/src/components/ui/sheet.tsx	Localize sheet close button accessibility label.
frontend/src/components/ui/dialog.tsx	Localize dialog close labels/buttons.
frontend/src/components/ui/breadcrumb.tsx	Localize breadcrumb aria label and “more” screen-reader label.
frontend/src/components/tables/users/data-table.tsx	Localize users table search placeholder and empty state.
frontend/src/components/tables/users/columns.tsx	Localize user table column headers, role/provider labels, and delete flows.
frontend/src/components/tables/repositories/data-table.tsx	Localize repositories table search placeholder and empty state.
frontend/src/components/tables/repositories/columns.tsx	Localize repository table headers/status labels and action/menu labels.
frontend/src/components/tables/data-table-view-options.tsx	Localize column options menu labels.
frontend/src/components/tables/data-table-column-header.tsx	Localize sort/hide column menu items.
frontend/src/components/tables/applications/data-table.tsx	Localize applications table empty state.
frontend/src/components/tables/applications/columns.tsx	Localize application table headers and action menu labels.
frontend/src/components/status-badge.tsx	Localize sync/health status badge labels.
frontend/src/components/navbar.tsx	Localize navigation labels, menu items, and accessibility labels.
frontend/src/components/mode-toggle.tsx	Localize theme toggle labels and aria-label.
frontend/src/components/dialogs/upsert-user-dialog.tsx	Localize upsert user dialog (schema messages, labels, toasts, buttons).
frontend/src/components/dialogs/upsert-repository.tsx	Localize repository connection dialog/stepper text and errors.
frontend/src/components/dialogs/upsert-oidc-provider-dialog.tsx	Localize OIDC provider dialog (schema messages, labels, toasts, buttons).
frontend/src/components/dialogs/upsert-application.tsx	Localize application dialog (schema messages, labels, toasts, buttons).
frontend/src/components/dialogs/upsert-agent.tsx	Localize agent dialog (schema messages, labels, toasts, buttons).
frontend/src/components/dialogs/force-password-change-dialog.tsx	Localize forced password change dialog and validation/toasts.
frontend/src/components/dialogs/copy-value-dialog.tsx	Localize copy dialog default labels.
frontend/src/components/dialogs/confirm-dialog.tsx	Localize confirmation dialog default strings.
frontend/src/components/copy-btn.tsx	Localize copy button default title.
frontend/src/components/cards/agents/data-cards.tsx	Localize agent cards search/empty state, actions, and toasts.
frontend/src/components/alerts/success-alert.tsx	Localize default success alert title/description.
frontend/src/components/alerts/error-alert.tsx	Localize default error alert title/description.
frontend/messages/en.json	Add/expand English message catalog for UI translation.
frontend/messages/de.json	Add/expand German message catalog for UI translation.

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