Add configurable output DPI setting (port of upstream PR #379)

Adds output_dpi field to Options (default 96.0) and passes it to the
GraphViz graph attributes. Higher DPI produces sharper PNG/PDF renders,
useful for print-quality harness documentation.

src/wireviz/wv_dataclasses.py

@@ -87,6 +87,7 @@ class Options:
     color_output_mode: ColorOutputMode = ColorOutputMode.EN_UPPER
     mini_bom_mode: bool = True
     template_separator: str = "."
+    output_dpi: Optional[float] = 96.0
     _pad: int = 0
     # TODO: resolve template and image paths during rendering, not during YAML parsing
     _template_paths: List = field(default_factory=list)

src/wireviz/wv_graphviz.py

@@ -632,6 +632,7 @@ def set_dot_basics(dot, options):
         bgcolor=options.bgcolor.html,
         nodesep="0.33",
         fontname=options.fontname,
+        dpi=f"{options.output_dpi}",
     )  # TODO: Add graph attribute: charset="utf-8",
     dot.attr(
         "node",