feat(docx): add hi-fidelity XML injections for tables, styles, lists, and sections; extend tools and tests

- Add feature flags: hi-fidelity-tables, hi-fidelity-styles, hi-fidelity-lists, hi-fidelity-sections
- Tables: inject true w:gridSpan/w:vMerge and w:tblGrid widths via post-build XML when enabled
- Styles: ensure TableHeader style in styles.xml; tag first row when headers present
- Lists: robust numbering.xml for ordered/unordered with multi-level definitions
- Sections: write tail w:sectPr with page size/orientation/margins
- Tools: expose new operations (sections, list items, images, hyperlinks, props, redaction, storage)
- Converters: add preference-aware methods for hi-fidelity export paths; HTML export tool
- Tests: add golden XML assertions gated by feature flags; keep default build green

This enables high-fidelity DOCX output while keeping pure-Rust paths by default.

Cargo.toml

@@ -57,6 +57,7 @@ usvg = "0.44"  # SVG parsing
 pulldown-cmark = "0.12"  # Markdown parsing
 html5ever = "0.29"  # HTML parsing
 comrak = "0.28"  # CommonMark parsing
+html-escape = "0.2"
 
 # Text extraction from DOCX
 dotext = "0.1"
@@ -107,6 +108,11 @@ pure-rust-pdf = []
 external-tools = ["headless_chrome", "wkhtmltopdf"]
 full = ["embedded-fonts", "pure-rust-pdf", "external-tools", "tera"]
 build-bin = []
+hi-fidelity = [] # placeholder feature flag for high-fidelity rendering backends
+hi-fidelity-tables = [] # enable XML injection for true table merges/widths
+hi-fidelity-sections = [] # enable XML injection for sectPr (page setup)
+hi-fidelity-styles = [] # enable XML injection for custom styles (e.g., TableHeader)
+hi-fidelity-lists = [] # enable XML injection for robust numbering definitions
 
 [build-dependencies]
 anyhow = "1.0"