Revert to crates.io usvg v0.46 and anyrender_svg v0.13

[nicoburns]

Summary

Removes the [patch.crates-io] overrides for usvg (DioxusLabs/resvg fork) and anyrender/anyrender_svg (DioxusLabs/anyrender fork branch), returning to pure crates.io dependencies while keeping SVG intrinsic-sizing behaviour:

• The forked usvg's Tree::intrinsic_dimensions is replaced by an in-Blitz SvgIntrinsicDimensions { width, height, view_box_size }, computed in parse_svg_image by re-parsing the root <svg>'s width/height/viewBox attributes with usvg::roxmltree + a direct svgtypes dep (matching usvg's own parsing: percentages kept unresolved, absent attrs None, viewBox validated as finite/positive). SvgImageData accessors (intrinsic_width, resolved_width, viewbox_aspect_ratio, ...) are unchanged in behaviour.
• usvg is downgraded 0.48.1 → 0.46.0, which is what crates.io anyrender_svg 0.13 requires. The fork branch's "don't apply SVG text transform twice" fix is only needed against usvg 0.48 ("Text nodes now inherit their absolute transform" changed in 0.48.0), so anyrender needs no new release.

Non-UTF-8 sources (e.g. SVGZ) skip the attribute re-parse and fall back to usvg::Tree::size, matching the pre-fork behaviour of having no declared dimensions.

Note: usvg 0.46 reverts SVG text rendering to the rustybuzz/ttf-parser stack (0.48 moved to harfrust/skrifa); this goes away again once upstream linebender/resvg#1119 ships and usvg can be re-bumped.

Link to Devin session: https://dioxus.staging.devinenterprise.com/sessions/14862dc9892246ca9c154ba95ceae878
Requested by: @nicoburns

WPT results

0 newly passing, 9 newly failing (net -9).

Full diff (9 changed tests)

- Pass => Fail css/css-flexbox/flex-aspect-ratio-img-column-013.html
- Pass => Fail css/css-flexbox/flex-aspect-ratio-img-column-014.html
- Pass => Fail css/css-flexbox/flex-aspect-ratio-img-column-015.html
- Pass => Fail css/css-flexbox/flex-aspect-ratio-img-row-008.html
- Pass => Fail css/css-flexbox/flex-aspect-ratio-img-row-009.html
- Pass => Fail css/css-flexbox/flex-aspect-ratio-img-row-010.html
- Pass => Fail css/css-flexbox/flex-aspect-ratio-img-row-011.html
- Pass => Fail css/css-sizing/aspect-ratio/replaced-element-039.html
- Pass => Fail css/css-sizing/aspect-ratio/replaced-element-040.html

_{Generated by the WPT workflow.}

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