Add .gitattributes: enforce LF line endings, mark binary files

Stops CRLF warnings on Windows and ensures consistent line endings
across all platforms.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitattributes

@@ -0,0 +1,17 @@
+# Force LF line endings for all text files
+* text=auto eol=lf
+
+# Explicitly mark binary files
+*.png binary
+*.jpg binary
+*.jpeg binary
+*.gif binary
+*.ico binary
+*.svg text eol=lf
+*.woff binary
+*.woff2 binary
+*.ttf binary
+*.eot binary
+*.zip binary
+*.gz binary
+*.tar binary