scoreview-engine v4.7.6-engine.4

release v4.7.6-engine.4

Security fixes from the audit (#44, issues #29-#43). Scores are checked
before the upstream reader runs: nesting depth, clef staff and segment
indices, repeat counts, staff ids, the version string and the zip
structure, with every deflate entry inflated once against its declared
size. A score can no longer pull another live score's pictures out of the
global image store, and 2.x text styles no longer carry over from one 2.x
score to the next. The wasm module is built with -fwasm-exceptions, so
engine exceptions become ordinary errors instead of aborts; after a real
trap the JS wrapper refuses further calls (EngineAbortedError) and the
worker wrapper terminates the worker. generateExcerpts is linear in the
part count (128 parts: 19.8 s -> 0.67 s).

Output is unchanged: the native corpus report is bit-identical to
v4.7.6-engine.3's for all 570 scores, SVG included, and the wasm gate
passes with the same waivers.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>