feat: add Open WebUI external web loader endpoint

Add /load endpoint for Open WebUI's WEB_LOADER_ENGINE=external integration.
Uses document.body.innerText for content extraction.

Configure in Open WebUI:
  WEB_LOADER_ENGINE=external
  EXTERNAL_WEB_LOADER_URL=http://byparr:8191/load
  EXTERNAL_WEB_LOADER_API_KEY=<OWUI_API_KEY env var>

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/owui_test.py

@@ -0,0 +1,81 @@
+from http import HTTPStatus
+from unittest.mock import patch
+
+import pytest
+from starlette.testclient import TestClient
+
+from main import app
+
+client = TestClient(app)
+
+
+def test_owui_load_basic():
+    """Test /load endpoint returns correct structure."""
+    response = client.post("/load", json={"urls": ["https://example.com"]})
+    assert response.status_code == HTTPStatus.OK
+    results = response.json()
+    assert len(results) == 1
+    assert "page_content" in results[0]
+    assert "metadata" in results[0]
+    assert results[0]["metadata"]["source"] == "https://example.com"
+
+
+def test_owui_load_multiple_urls():
+    """Test /load endpoint handles multiple URLs."""
+    urls = ["https://example.com", "https://example.org"]
+    response = client.post("/load", json={"urls": urls})
+    assert response.status_code == HTTPStatus.OK
+    results = response.json()
+    assert len(results) == 2
+    assert results[0]["metadata"]["source"] == urls[0]
+    assert results[1]["metadata"]["source"] == urls[1]
+
+
+def test_owui_load_extracts_content():
+    """Test /load endpoint extracts non-empty content from a real page."""
+    response = client.post("/load", json={"urls": ["https://example.com"]})
+    assert response.status_code == HTTPStatus.OK
+    results = response.json()
+    # example.com has minimal content but should have something
+    assert len(results[0]["page_content"]) > 0
+
+
+def test_owui_load_auth_required():
+    """Test /load returns 401 when API key is set but not provided."""
+    with patch("src.owui._API_KEY", "test-secret-key"):
+        response = client.post("/load", json={"urls": ["https://example.com"]})
+        assert response.status_code == HTTPStatus.UNAUTHORIZED
+
+
+def test_owui_load_auth_invalid():
+    """Test /load returns 401 when API key is wrong."""
+    with patch("src.owui._API_KEY", "test-secret-key"):
+        response = client.post(
+            "/load",
+            json={"urls": ["https://example.com"]},
+            headers={"Authorization": "Bearer wrong-key"},
+        )
+        assert response.status_code == HTTPStatus.UNAUTHORIZED
+
+
+def test_owui_load_auth_valid():
+    """Test /load succeeds with correct API key."""
+    with patch("src.owui._API_KEY", "test-secret-key"):
+        response = client.post(
+            "/load",
+            json={"urls": ["https://example.com"]},
+            headers={"Authorization": "Bearer test-secret-key"},
+        )
+        assert response.status_code == HTTPStatus.OK
+
+
+def test_owui_load_invalid_url_graceful():
+    """Test /load returns empty content for unreachable URLs."""
+    response = client.post(
+        "/load", json={"urls": ["https://this-domain-does-not-exist-12345.invalid"]}
+    )
+    assert response.status_code == HTTPStatus.OK
+    results = response.json()
+    assert len(results) == 1
+    assert results[0]["page_content"] == ""
+    assert "this-domain-does-not-exist" in results[0]["metadata"]["source"]