refactor(agent): rename md_to_html to readme_processor, fix section extraction, widget parsing, and list_base_models

- Rename md_to_html.py → readme_processor.py (file no longer just HTML conversion)
- _extract_section: include YAML frontmatter, use heading-level-aware forward
  walk (sub-headings under # are included), increase walk limit past 30 lines
- _is_heading: exclude </hN> closing tags from boundary detection
- _heading_level: new helper for heading-level-aware section matching
- css: yield 0 for heading like closing tags, was unexpectedly caught by _is_heading
- extract_gallery_images: fix YAML block scalar (text: >-) prompt extraction;
  use endswith instead of == to detect the block marker
- _strip_widget_section: add to clean_readme_for_llm (widget text is handled
  by post-processor, not needed in LLM prompt)
- _strip_standalone_images: keep markdown image URLs intact for LLM preview
  extraction (was stripping to alt text only)
- list_base_models: switch from scanner-cache aggregation to
  CivitaiBaseModelService.get_base_models() - always returns full list
- Ollama: add num_ctx=32768 to payload options so thinking models have room
  to both reason and produce output
- Add tests/agent_cli/test_readme_processor.py: 59 tests covering extraction,
  cleaning, section matching, heading detection
- Update existing tests for behavioral changes

py/services/agent/agent_service.py

@@ -31,7 +31,7 @@ from ..llm_service import LLMService
 from ..websocket_manager import ws_manager
 from .post_processor import PostProcessor
 from .skill_registry import SkillRegistry
-from .skills.enrich_hf_metadata.md_to_html import (
+from .skills.enrich_hf_metadata.readme_processor import (
     clean_readme_for_llm,
     extract_relevant_section,
 )
@@ -397,6 +397,10 @@ class AgentService:
                 cleaned = clean_readme_for_llm(readme) if readme else ""
             context["readme_content"] = cleaned if cleaned else "(README not available)"
             context["readme_content_full"] = readme or ""
+            logger.info(
+                "Cleaned README for %s (%d chars): ---BEGIN---\n%s\n---END---",
+                repo, len(cleaned), cleaned[:800] if cleaned else "(empty)",
+            )
 
         try:
             context["base_models"] = await list_base_models()