Add .gitattributes for LF normalization

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: scottconverse

.gitattributes

@@ -0,0 +1,14 @@
+# Normalize line endings: text files are LF in the repo.
+* text=auto eol=lf
+
+# Treat SCAD and common asset types explicitly
+*.scad   text eol=lf
+*.md     text eol=lf
+*.yml    text eol=lf
+*.svg    text eol=lf
+*.ps1    text eol=lf
+
+# Binary assets (if any are added later)
+*.stl    binary
+*.3mf    binary
+*.png    binary