Reject displayId values >100k (corrupted update-field data) to avoid
pointless DBC lookups and log spam. Add fileExists() guard before
using base texture path in 4 equipment compositing code paths that
were falling through without checking, causing excessive "Texture not
found" warnings when users have incomplete MPQ extractions.
When spline parsing consumes the wrong number of bytes, the subsequent
blockCount read lands on garbage data (e.g. 71 instead of ~5 for UNIT).
Previously the parser logged a warning but continued, reading garbage
mask/field data until hitting truncation. Now it returns false for
CREATE_OBJECT blocks with suspicious counts, letting the block loop
skip cleanly to the next entity.
Also downgrade ~44 diagnostic LOG_WARNING messages to LOG_DEBUG across
17 files (equipment, transport, DBC, heartbeat, chat, GO raypick, etc.)
to reduce log noise and make real warnings visible.
