feat: custom fields per project

Text, number, date or option-list fields defined in the project settings
(archived, never removed; their type is fixed once saved). Tickets hold
them, edited in the side panel, listed under the title and filtered by
option in the list view; also over GraphQL, REST (?field=ID:value) and MCP.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/e2e/tracker.e2e-spec.ts

@@ -1168,4 +1168,115 @@ describe('task-stream (e2e)', () => {
       history.body.map((h: { actor: { name: string } }) => h.actor.name),
     ).toContain('TaskStream');
   });
+
+  it('adds custom fields to a project and lets tickets hold and filter by them', async () => {
+    const key = 'C' + Date.now().toString(36).slice(-5).toUpperCase();
+    await rest('token-ana', 'POST', '/projects', { key, name: key });
+    const project = await eventually(
+      () => rest('token-ana', 'GET', `/projects/${key}`),
+      (r) => r.status === 200,
+    );
+    const settings = project.body['settings'];
+    expect(settings.customFields).toEqual([]);
+
+    // REST: define them (a client that leaves them out keeps them).
+    const fields = [
+      {
+        id: 'BROWSER',
+        name: 'Navegador',
+        type: 'SELECT',
+        options: ['Chrome', 'Safari'],
+      },
+      { id: 'COST', name: 'Coste', type: 'NUMBER' },
+    ];
+    expect(
+      (
+        await rest('token-ana', 'PUT', `/projects/${key}/settings`, {
+          ...settings,
+          customFields: fields,
+        })
+      ).status,
+    ).toBe(200);
+    await eventually(
+      () => rest('token-ana', 'GET', `/projects/${key}`),
+      (r) => r.body['settings'].customFields.length === 2,
+    );
+    const { customFields: _left, ...older } = settings;
+    expect(
+      (await rest('token-ana', 'PUT', `/projects/${key}/settings`, older))
+        .status,
+    ).toBe(200);
+
+    // REST: a ticket with values; a wrong one is refused.
+    const created = await rest('token-ana', 'POST', `/projects/${key}/issues`, {
+      type: 'BUG',
+      title: 'Pago roto',
+      customFields: { BROWSER: 'Safari', COST: '1,5' },
+    });
+    expect(created.status).toBe(201);
+    const ticket = created.body['key'] as string;
+    const issue = await eventually(
+      () => rest('token-ana', 'GET', `/issues/${ticket}`),
+      (r) => r.status === 200,
+    );
+    expect(issue.body['customFields']).toEqual({
+      BROWSER: 'Safari',
+      COST: '1.5',
+    });
+    expect(
+      (
+        await rest('token-ana', 'PATCH', `/issues/${ticket}`, {
+          customFields: { BROWSER: 'Edge' },
+        })
+      ).status,
+    ).toBe(400);
+    await rest('token-ana', 'POST', `/projects/${key}/issues`, {
+      type: 'BUG',
+      title: 'Otro',
+      customFields: { BROWSER: 'Chrome' },
+    });
+
+    // GraphQL: change one, clear another; filter by value.
+    await gql(
+      'token-ana',
+      `mutation($i: UpdateIssueInput!) { updateIssue(input: $i) { version } }`,
+      {
+        i: {
+          issueId: issue.body['id'],
+          customFields: [
+            { fieldId: 'BROWSER', value: 'Chrome' },
+            { fieldId: 'COST', value: null },
+          ],
+        },
+      },
+    );
+    const filtered = await eventually(
+      () =>
+        gql(
+          'token-ana',
+          `query($f: IssueFilterInput!) { issues(filter: $f) { total items { key customFields { fieldId value } } } }`,
+          {
+            f: {
+              projectId: project.body['id'],
+              customFields: [{ fieldId: 'BROWSER', value: 'Chrome' }],
+            },
+          },
+        ),
+      (d) => d['issues'].total === 2,
+    );
+    expect(
+      filtered['issues'].items.find((i: { key: string }) => i.key === ticket)
+        .customFields,
+    ).toEqual([{ fieldId: 'BROWSER', value: 'Chrome' }]);
+    const bySafari = await rest(
+      'token-ana',
+      'GET',
+      `/projects/${key}/issues?field=BROWSER:Safari`,
+    );
+    expect(bySafari.body['total']).toBe(0);
+    const history = await rest('token-ana', 'GET', `/issues/${ticket}/history`);
+    expect(
+      history.body.map((h: { summary: string }) => h.summary).join(' | '),
+    ).toContain('los campos personalizados');
+  });
 });