feat(testing): add end-to-end HTML scraping and parsing tests with typed parsers

- Add smart httpx MockTransport routing based on endpoint paths
- Render HTML fixtures via Jinja templates populated from JSON data
- Introduce explicit, typed HTML parsers for semantic and table-based content
- Add end-to-end tests covering scraper → content → parser → Pydantic models
- Enforce explicit output contracts and avoid default dict-based parsing

tests/mocks/table.json

@@ -0,0 +1,14 @@
+{
+  "title": "Table Test Page",
+  "description": "HTML page with a table for parsing tests",
+  "heading": "Sample Table",
+  "table_id": "data-table",
+  "columns": ["Name", "Age", "City"],
+  "rows": [
+    ["Alice", "30", "London"],
+    ["Bob", "25", "New York"],
+    ["Charlie", "35", "Berlin"]
+  ],
+  "link_url": "https://example.org/details",
+  "link_text": "Details"
+}