feat: Integrate standalone HTML converter with pipeline

- Add convert_file_to_html() function for programmatic use
- Modify save_all_markmaps() to support standalone tool option
- Add configuration option use_standalone_tool in config.yaml
- Update pipeline to check config and use appropriate converter
- Maintain backward compatibility (default: internal converter)
- Update README with integration instructions

This allows decoupling (tool can run independently) while enabling
integration (pipeline can call it programmatically).

Author: lufftw

tools/ai-markmap-agent/README.md

@@ -215,6 +215,42 @@ python translate_only.py --source en --target zh-TW
 
 # Also generate HTML
 python translate_only.py --html
+
+### Standalone HTML Converter
+
+For converting Markdown files to HTML without running the full pipeline:
+
+```bash
+# Basic conversion (output: input.html)
+python convert_to_html.py input.md
+
+# Specify output file
+python convert_to_html.py input.md -o output.html
+
+# Custom title
+python convert_to_html.py input.md -t "My Mind Map"
+
+# Use custom template
+python convert_to_html.py input.md --template templates/custom.html
+```
+
+This tool is **completely independent** of the main pipeline and only requires:
+- Python 3.10+
+- `jinja2` package
+
+It can be used to convert any Markmap Markdown file to interactive HTML.
+
+### Integration with Pipeline
+
+The standalone tool can be integrated with the main pipeline. To use it instead of the internal converter, set in `config/config.yaml`:
+
+```yaml
+output:
+  html:
+    use_standalone_tool: true  # Use convert_to_html.py instead of internal converter
+```
+
+This maintains **decoupling** (the tool can run independently) while allowing **integration** (the pipeline can call it programmatically).
 ```
 
 ### API Keys

tools/ai-markmap-agent/config/config.yaml

@@ -347,6 +347,9 @@ output:
 
   html:
     template: "templates/markmap.html"
+    # Use standalone convert_to_html.py tool instead of internal converter
+    # This allows decoupling while maintaining integration
+    use_standalone_tool: false  # Set to true to use convert_to_html.py
     include_styles: true
     include_scripts: true
     title: "AI Evolved Markmap"