fix(render): iter 86 — diagnose kpsewhich lookups for cmcsc10 + rm-lmb10
Iter 85 confirmed every relevant file is on disk in BOTH the flat
FOREST_TEX_DIR AND the canonical FOREST_TEXMF tree (rm-*.tfm at
fonts/tfm/public/lm/, cmcsc10.pfb mirrored to fonts/type1/public/cm/,
ls-R indexed, psfonts.map has the direct mapping). But the SVG bytes
DID NOT CHANGE (48088 across iters 80-85), and the warnings about
'can't find rm-lmb10.tfm' persist.
Hypothesis: kpathsea at iter staging context AND at dvisvgm runtime
search different paths — TEXMFAUXTREES is only exported inside the
dvisvgm shim (per-call), so a sanity kpsewhich here wouldn't pick it
up unless we set it manually.
iter 86 runs kpsewhich in 3 contexts:
(a) bare environment (what build sees by default)
(b) with TEXMFAUXTREES explicitly set (what shim sees)
(c) dvisvgm --version + --list-fonts (any config hints)
Refs #2
[AGENT: kael]