feat: add missing project files and fix architecture compliance

- Add LICENSE file (MIT)
- Add CONTRIBUTING.md with generator-first workflow guidelines
- Add Makefile with comprehensive development commands
- Add .editorconfig for consistent code formatting
- Add CHANGELOG.md for version tracking
- Remove inconsistent non-variant files that bypassed generator architecture
- Fix installation script to use variant-specific paths (prevent config overwriting)

cli/delta/template.txt

@@ -11,12 +11,12 @@
     line-numbers-right-style = cyan
     line-numbers-minus-style = red
     line-numbers-plus-style = green
-    line-numbers-zero-style = "#{{gray2}}"
-    minus-style = syntax "#{{red}}"
-    minus-emph-style = syntax "#{{red}}"
-    plus-style = syntax "#{{green}}"
-    plus-emph-style = syntax "#{{green}}"
+    line-numbers-zero-style = "{{gray2}}"
+    minus-style = syntax "{{red}}"
+    minus-emph-style = syntax "{{red}}"
+    plus-style = syntax "{{green}}"
+    plus-emph-style = syntax "{{green}}"
     zero-style = syntax
     blame-code-style = syntax
     blame-format = "{author:<18} ({commit:>8}) {timestamp:^16} "
-    blame-palette = "#{{gray1}}" "#{{gray2}}" "#{{gray3}}"
+    blame-palette = "{{gray1}}" "{{gray2}}" "{{gray3}}"