refactor(tests): use omniread public API instead of internal module imports

- Replace deep imports with top-level omniread exports in tests
- Ensure tests validate only the supported public API surface
- Align HTML and PDF tests with documented library usage

tests/conftest.py

@@ -4,10 +4,17 @@ import httpx
 from pathlib import Path
 from jinja2 import Environment, BaseLoader
 
-from omniread.core.content import ContentType
-from omniread.html.scraper import HTMLScraper
-from omniread.pdf.client import FileSystemPDFClient
-from omniread.pdf.scraper import PDFScraper
+from omniread import (
+    # core
+    ContentType,
+
+    # html
+    HTMLScraper,
+
+    # pdf
+    FileSystemPDFClient,
+    PDFScraper,
+)
 
 
 MOCK_HTML_DIR = Path(__file__).parent / "mocks" / "html"