feat: add certificate export and upload dialogs

- Implemented CertificateExportDialog for exporting certificates in various formats (PEM, PFX, DER) with options to include private keys and set passwords.
- Created CertificateUploadDialog for uploading certificates, including validation and support for multiple file types (certificates, private keys, chain files).
- Updated DeleteCertificateDialog to use 'domains' instead of 'domain' for consistency.
- Refactored BulkDeleteCertificateDialog and DeleteCertificateDialog tests to accommodate changes in certificate structure.
- Added FileDropZone component for improved file upload experience.
- Enhanced translation files with new keys for certificate management features.
- Updated Certificates page to utilize the new CertificateUploadDialog and clean up the upload logic.
- Adjusted Dashboard and ProxyHosts pages to reflect changes in certificate data structure.

frontend/src/api/__tests__/certificates.test.ts

@@ -17,12 +17,14 @@ describe('certificates API', () => {
   });
 
   const mockCert: Certificate = {
-    id: 1,
-    domain: 'example.com',
+    uuid: 'abc-123',
+    domains: 'example.com',
     issuer: 'Let\'s Encrypt',
     expires_at: '2023-01-01',
     status: 'valid',
     provider: 'letsencrypt',
+    has_key: true,
+    in_use: false,
   };
 
   it('getCertificates calls client.get', async () => {
@@ -47,7 +49,7 @@ describe('certificates API', () => {
 
   it('deleteCertificate calls client.delete', async () => {
     vi.mocked(client.delete).mockResolvedValue({ data: {} });
-    await deleteCertificate(1);
-    expect(client.delete).toHaveBeenCalledWith('/certificates/1');
+    await deleteCertificate('abc-123');
+    expect(client.delete).toHaveBeenCalledWith('/certificates/abc-123');
   });
 });