DOCX: conditional table styles ignore border definitions

[developer0hye]

Problem

DOCX table styles can define base w:tblBorders and region-specific w:tcBorders inside w:tblStylePr. office2pdf's conditional table-style resolver currently carries only background, text color, and bold state, so the declared borders are lost.

In the public complex-table fixture, Word draws white grid borders over black/gray fills. Current main draws black fallback borders. Removing fallback gridlines in #277 does not resolve the root cause because the style's white borders would still be absent.

Expected behavior

Parse and cascade base and conditional table-style borders, including nil sides, inside horizontal/vertical borders, edge regions, and merged-cell spans, while preserving direct cell-border precedence.

Related: #195, #203

Side-by-side (GT left, office2pdf right)

[developer0hye]

Fixed by PR #317 (merged).

Table styles' base w:tblBorders and per-region w:tcBorders now flow through the conditional resolver: each cell's edges resolve from the base grid (outer edges on boundary cells, insideH/insideV on interior edges), and an active special region's explicit sides override the matching edges of its own cells (e.g. a firstRow bottom border lands on the header row's bottom edge). Explicit cell tcBorders still win.

Verified on the complex-table fixture at 150 DPI — the white grid now separates the black/gray banded cells like Word (see the PR's GT/before/after). The fixture's serif body font was the separate theme-font issue, fixed in #316.