The Web UI re-parses drawing SVG into its own element model instead of
rendering it raw, which makes hand-assembled SVG error-prone for LLM
callers. The new tool assembles the SVG server-side, mirroring what the
Web UI itself serializes for text drawings:
- XML-escaped text content, validated color (#RGB/#RGBA/#RRGGBB/
#RRGGBBAA) and font family (attribute-safe charset)
- multi-line support: literal newlines render as stacked lines in the
Web UI (tspan split), width/height computed from the longest line
- pt-aware sizing: the Web UI renders font-size in pt (1pt = 4/3 px),
so width uses a 0.8/char factor for monospace (1.0 proportional) and
line height 1.9 x font_size, instead of the px-based 0.62 estimate
- ET.fromstring pre-check so bad input fails loudly instead of hitting
the controller's silent drop of unparseable 500+ char SVG
- computed width/height/line_height returned for label layout
Also correct the raw drawing_create docstring: root width/height are
required (the parser reads them for the selection box), x/y on rect are
ignored, <g> is unsupported, <path> is re-interpreted as a freehand
curve, and the old examples lacked the mandatory root dimensions.
