PPTX: style-referenced outlines (lnRef) are not applied to preset shapes

[developer0hye]

Problem

Shapes whose outline comes from the style matrix (<p:style><a:lnRef idx="..."> with a scheme color transform) render without any stroke — the pentagon in libreoffice/shape-text-rotate.pptx has a dark accent1-shaded border in PowerPoint but none in our output. Explicit <a:ln> strokes work; the lnRef indirection is dropped.

Expected

Resolve lnRef against the theme's line style list (like fillRef resolves fills) and apply the referenced stroke with its color transform.

Found during the after-image re-audit of #286.

Related: #213

[developer0hye]

Fixed by PR #322 (merged).

Shapes whose outline comes from the style matrix (<p:style><a:lnRef>) now render their stroke. Two root causes: the outline width lives in the theme lnStyleLst referenced by lnRef idx (now parsed into ThemeData and used as the fallback width), and the lnRef scheme color carrying a shade/tint transform arrives as a Start event that only the Empty-event arm handled (now resolved from Start events too, for lnRef/fillRef/fontRef). Verified on the shape-text-rotate fixture: the pentagon shows its accent1-shaded outline matching PowerPoint GT.