feat: enhance model caching and output modalities handling

- Updated `refresh_models_cache` to include output modalities in the models cache.
- Added `get_model_output_modalities` function to retrieve output modalities for a specific model.
- Modified tests to cover new functionality for output modalities.
- Updated OpenRouter video generation functions to support audio generation and improved error handling.
- Enhanced dashboard to display generated images and videos.
- Refactored frontend templates to accommodate new data structures for generated content.
- Adjusted tests to validate changes in model handling and dashboard rendering.

Co-authored-by: Copilot <copilot@github.com>

frontend/tests/test_frontend.py

@@ -151,7 +151,8 @@ def test_dashboard_renders_user_info(client):
     me_mock = _mock_response(
         200, {"id": "1", "email": "u@example.com", "role": "user"})
     images_mock = _mock_response(200, [])
-    with patch("frontend.app.main.httpx.request", side_effect=[me_mock, images_mock]):
+    gen_images_mock = _mock_response(200, [])
+    with patch("frontend.app.main.httpx.request", side_effect=[me_mock, images_mock, gen_images_mock]):
         resp = client.get("/dashboard")
     assert resp.status_code == 200
     assert b"u@example.com" in resp.data
@@ -531,19 +532,43 @@ def test_dashboard_shows_uploaded_images(client):
         {"id": "img-1", "filename": "cat.png", "content_type": "image/png",
          "size_bytes": 1024, "created_at": "2026-04-29T10:00:00"},
     ])
-    with patch("frontend.app.main.httpx.request", side_effect=[me_mock, images_mock]):
+    gen_images_mock = _mock_response(200, [])
+    with patch("frontend.app.main.httpx.request", side_effect=[me_mock, images_mock, gen_images_mock]):
         resp = client.get("/dashboard")
     assert resp.status_code == 200
     assert b"cat.png" in resp.data
     assert b"img-1" in resp.data
 
 
+def test_dashboard_shows_generated_images(client):
+    _set_auth(client)
+    me_mock = _mock_response(
+        200, {"id": "1", "email": "u@example.com", "role": "user"})
+    images_mock = _mock_response(200, [])
+    gen_images_mock = _mock_response(200, [
+        {
+            "id": "gen-1",
+            "model_id": "google/gemini-2.5-flash-image",
+            "prompt": "A cat on the moon",
+            "image_data": "data:image/png;base64,abc123",
+            "created_at": "2026-04-29T10:00:00",
+        }
+    ])
+    with patch("frontend.app.main.httpx.request", side_effect=[me_mock, images_mock, gen_images_mock]):
+        resp = client.get("/dashboard")
+    assert resp.status_code == 200
+    assert b"Generated images" in resp.data
+    assert b"A cat on the moon" in resp.data
+    assert b"data:image/png;base64,abc123" in resp.data
+
+
 def test_dashboard_no_images_section_when_empty(client):
     _set_auth(client)
     me_mock = _mock_response(
         200, {"id": "1", "email": "u@example.com", "role": "user"})
     images_mock = _mock_response(200, [])
-    with patch("frontend.app.main.httpx.request", side_effect=[me_mock, images_mock]):
+    gen_images_mock = _mock_response(200, [])
+    with patch("frontend.app.main.httpx.request", side_effect=[me_mock, images_mock, gen_images_mock]):
         resp = client.get("/dashboard")
     assert resp.status_code == 200
     assert b"Uploaded reference images" not in resp.data