[GIT] Slim delta, colorMoved, section hunk headers, wsdiff alias

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

gitconfig/attributes

@@ -0,0 +1,6 @@
+# hunk headers show the enclosing heading/section
+*.md diff=markdown
+gitconfig diff=ini
+*.gitconfig diff=ini
+*.ini diff=ini
+*.toml diff=ini