feat(svg): SvgPath.parse - full SVG path grammar to native PathNode curves

[DemchaAV]

What

The SVG milestone the path workstream was building toward: SvgPath.parse(d) (+ viewBox overload) in the new document.svg package lowers the complete SVG 1.1 path grammar into normalized, y-flipped DocumentPathSegments, and PathBuilder.svg(svgPath) drops them straight into addPath(...) — any icon's d string renders as native PDF curves.

• Grammar: absolute/relative M L H V C S Q T A Z, implicit repetition (moveto→lineto chains), exact quadratic→cubic elevation, S/T control-point reflection, elliptical arcs via the W3C endpoint-to-center algorithm (radii correction, ≤90° cubic slices), single-character arc flags (a1 1 0 011 1 parses).
• Normalization against the viewBox (icon workflow, keeps designed padding) or the tight bounding box; SVG y-down flips to our y-up; fills keep SVG's default non-zero winding.
• Syntax errors are IllegalArgumentExceptions carrying the character position.
• Scanner/state machine extracted into package-private SvgPathParser pre-commit (500-line rule); every branch is driven through the public-API tests.

Verification

• 14 SvgPathTest cases: triangle/relative/H-V/implicit-lineto, exact quad elevation values, S/T reflection coordinates, quarter-arc κ≈0.5523 check, 270°→3 slices, zero-radius arc→line, compact flags, golden Material heart end-to-end (all coordinates inside the unit box), flat-path degeneracy, six error contracts.
• PathBuilderTest.svgBridgeAppendsParsedSegments.
• Example renders the Material heart at 72pt via the DSL — regenerated vector-path.pdf preview eyeballed: orientation correct, curves smooth, single page.
• API hygiene green (new package ships package-info); full gate ./mvnw verify -pl . — 1276 tests, 0 failures, BUILD SUCCESS.