Add .gitattributes to enforce LF line endings

Prevents CRLF contamination from Windows-origin files.
All text files normalized to LF; binary extensions excluded.

.gitattributes

@@ -0,0 +1,36 @@
+# Normalize line endings to LF on commit
+* text=auto eol=lf
+
+# Force LF for all source files (prevents CRLF contamination)
+*.py text eol=lf
+*.c text eol=lf
+*.h text eol=lf
+*.js text eol=lf
+*.mjs text eol=lf
+*.ts text eol=lf
+*.json text eol=lf
+*.md text eol=lf
+*.mdx text eol=lf
+*.yml text eol=lf
+*.yaml text eol=lf
+*.toml text eol=lf
+*.cfg text eol=lf
+*.txt text eol=lf
+*.css text eol=lf
+*.astro text eol=lf
+*.html text eol=lf
+*.svg text eol=lf
+Makefile text eol=lf
+Dockerfile text eol=lf
+*.sh text eol=lf
+
+# Binary files — leave as-is
+*.bin binary
+*.ihx binary
+*.hex binary
+*.png binary
+*.jpg binary
+*.gif binary
+*.ico binary
+*.woff binary
+*.woff2 binary