Fix exclude_pending and mls_only filters not working with raw return type

When return_type="raw" was specified, the exclude_pending and mls_only
parameters were ignored because these filters only existed in
process_property(), which is bypassed for raw data returns.

Changes:
- Added _apply_raw_data_filters() method to handle client-side filtering
  for raw data
- Applied the filter in search() method after sorting but before returning
- Fixed exclude_pending to check flags.is_pending and flags.is_contingent
- Fixed mls_only to check source.id (not mls.id which doesn't exist in raw data)
- Added comprehensive tests for both filters with raw data

Fixes #140

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "homeharvest"
-version = "0.7.2"
+version = "0.7.3"
 description = "Real estate scraping library"
 authors = ["Zachary Hampton <zachary@bunsly.com>", "Cullen Watson <cullen@bunsly.com>"]
 homepage = "https://github.com/ZacharyHampton/HomeHarvest"