New subdirectory packages/pen-core/src/element-builders/ with
12 pure tree-build functions matching pen-mcp's add_*_v0 family.
Browser-safe (no node:fs, no document-manager) — meant to be
imported by both pen-mcp handlers (server) and apps/web client
shims (embedded orchestrator) so the tree shape is byte-identical
across paths, eliminating drift by construction.
Covered: buildCardRow, buildMetricRow, buildBottomNav,
buildSectionHeader, buildTopNavBar, buildHeading, buildBodyText,
buildTextButton, buildSearchBar, buildListRow. Plus helpers
(assignIdsRecursively, buildScrollWrapper, ElementTree type) and
cjk-detect (detectCjkScript + cjkFontFamily for heading/body
text font dispatch per repo's CJK contract in text-rules.md).
Re-exported from pen-core's main barrel. Pure additive change —
no existing callers affected. Consumers switched in a following
commit to avoid mixing refactor + infrastructure in one review.
b006997ca4