Fix corrupted glyphicons webfont files causing decode failures

The previous gulp-copy refresh (3111347) mangled the binary
eot/ttf/woff/woff2 files through a text-mode path, replacing invalid
byte sequences with U+FFFD and desyncing each file's internal length
header from its actual size — hence the browser's "Failed to decode
downloaded font" error in production. Reverted the four files to the
last known-good (pre-corruption) bytes and marked font extensions as
binary in .gitattributes so text=auto can never normalize them again.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitattributes

@@ -44,6 +44,15 @@
 #*.png   binary
 #*.gif   binary
 
+###############################################################################
+# Web font files must never be normalized (they are binary, not text).
+###############################################################################
+*.woff   binary
+*.woff2  binary
+*.ttf    binary
+*.eot    binary
+*.otf    binary
+
 ###############################################################################
 # diff behavior for common document formats
 #