Feat: Support multipart/mixed (#7155)

* feat(): support multipart mixed

fix: support vars interpolation on mixed multi-part

Update packages/bruno-electron/src/ipc/network/interpolate-vars.js

Co-authored-by: Timon <39559178+Its-treason@users.noreply.github.com>

refactor: use startsWith

feat: best effort for other multipart/* contentypes

* feat: enhance variable interpolation for multipart requests

- Updated `interpolateVars` function to support interpolation in multipart/form-data and multipart/mixed requests.
- Added handling for empty multipart arrays and parts with missing or undefined values.
- Improved type checks for content types to ensure proper interpolation behavior.

Includes new tests to validate the interpolation functionality for multipart requests.

* fix: normalize error handling in sendRequest and improve test reliability

---------

Co-authored-by: Alfonso Presa <alfonso-presa@users.noreply.github.com>

packages/bruno-electron/tests/network/interpolate-vars.spec.js

@@ -294,4 +294,136 @@ describe('interpolate-vars: interpolateVars', () => {
       expect(result.data).toEqual(undefined);
     });
   });
+
+  describe('Multipart body (multipart/form-data and multipart/mixed)', () => {
+    it('interpolates value in each part when Content-Type is multipart/form-data', () => {
+      const request = {
+        method: 'POST',
+        url: 'http://api.example/upload',
+        headers: { 'Content-Type': 'multipart/form-data; boundary=----boundary' },
+        data: [
+          { name: 'field1', value: '{{token}}', type: 'text' },
+          { name: 'field2', value: 'static', type: 'text' },
+          { name: 'field3', value: '{{prefix}}-suffix', type: 'text' }
+        ]
+      };
+
+      const result = interpolateVars(
+        request,
+        { token: 'secret123', prefix: 'my' },
+        null,
+        null
+      );
+
+      expect(result.data).toEqual([
+        { name: 'field1', value: 'secret123', type: 'text' },
+        { name: 'field2', value: 'static', type: 'text' },
+        { name: 'field3', value: 'my-suffix', type: 'text' }
+      ]);
+    });
+
+    it('interpolates value in each part when Content-Type is multipart/mixed', () => {
+      const request = {
+        method: 'POST',
+        url: 'http://api.example/send',
+        headers: { 'Content-Type': 'multipart/mixed; boundary=----mixed' },
+        data: [
+          { name: 'part1', value: '{{envVar}}', type: 'text' },
+          { name: 'part2', value: '{{another}}', type: 'text' }
+        ]
+      };
+
+      const result = interpolateVars(
+        request,
+        { envVar: 'first', another: 'second' },
+        null,
+        null
+      );
+
+      expect(result.data).toEqual([
+        { name: 'part1', value: 'first', type: 'text' },
+        { name: 'part2', value: 'second', type: 'text' }
+      ]);
+    });
+
+    it('leaves part keys (name, type, etc.) intact and only interpolates value', () => {
+      const request = {
+        method: 'POST',
+        url: 'http://api.example/upload',
+        headers: { 'Content-Type': 'multipart/form-data' },
+        data: [
+          { name: 'file', value: '{{path}}', type: 'file', fileName: 'doc.pdf' }
+        ]
+      };
+
+      const result = interpolateVars(request, { path: '/tmp/doc.pdf' }, null, null);
+
+      expect(result.data).toHaveLength(1);
+      expect(result.data[0].name).toBe('file');
+      expect(result.data[0].type).toBe('file');
+      expect(result.data[0].fileName).toBe('doc.pdf');
+      expect(result.data[0].value).toBe('/tmp/doc.pdf');
+    });
+
+    it('handles empty multipart array', () => {
+      const request = {
+        method: 'POST',
+        url: 'http://api.example/upload',
+        headers: { 'Content-Type': 'multipart/form-data' },
+        data: []
+      };
+
+      const result = interpolateVars(request, { x: 'y' }, null, null);
+
+      expect(result.data).toEqual([]);
+    });
+
+    it('handles part with missing or undefined value', () => {
+      const request = {
+        method: 'POST',
+        url: 'http://api.example/upload',
+        headers: { 'Content-Type': 'multipart/form-data' },
+        data: [
+          { name: 'a', value: '{{present}}' },
+          { name: 'b' },
+          { name: 'c', value: undefined }
+        ]
+      };
+
+      const result = interpolateVars(request, { present: 'ok' }, null, null);
+
+      expect(result.data[0].value).toBe('ok');
+      expect(result.data[1].value).toBeUndefined();
+      expect(result.data[2].value).toBeUndefined();
+    });
+
+    it('preserves raw string body when Content-Type is multipart/mixed (manually constructed multipart)', () => {
+      // Equivalent to: curl -X POST https://httpbin.dev/post \
+      //   -H 'content-type: multipart/mixed; boundary=TestBoundary123' \
+      //   --data '--TestBoundary123\r\nContent-Type: application/json\r\n\r\n{"test": true}\r\n--TestBoundary123--\r\n'
+      const rawMultipartBody = [
+        '--TestBoundary123',
+        'Content-Type: application/json',
+        '',
+        '{"test": true}',
+        '--TestBoundary123--',
+        ''
+      ].join('\r\n');
+
+      const request = {
+        method: 'POST',
+        url: 'https://httpbin.dev/post',
+        headers: { 'content-type': 'multipart/mixed; boundary=TestBoundary123' },
+        data: rawMultipartBody
+      };
+
+      const result = interpolateVars(request, {}, null, null);
+
+      expect(result.data).toBe(rawMultipartBody);
+      expect(result.data).toContain('--TestBoundary123');
+      expect(result.data).toContain('Content-Type: application/json');
+      expect(result.data).toContain('{"test": true}');
+      expect(result.data).toContain('--TestBoundary123--');
+    });
+  });
 });