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/atuin/template.txt

@@ -0,0 +1,29 @@
+# Everforest theme for Atuin
+# Generated from template - do not edit manually
+
+[colors]
+background = "{{bg}}"
+foreground = "{{fg}}"
+cursor = "{{yellow}}"
+selection_background = "{{bg1}}"
+selection_foreground = "{{fg}}"
+
+[colors.normal]
+black = "{{ansi_black}}"
+red = "{{ansi_red}}"
+green = "{{ansi_green}}"
+yellow = "{{ansi_yellow}}"
+blue = "{{ansi_blue}}"
+magenta = "{{ansi_purple}}"
+cyan = "{{ansi_aqua}}"
+white = "{{ansi_white}}"
+
+[colors.bright]
+black = "{{ansi_bright_black}}"
+red = "{{ansi_bright_red}}"
+green = "{{ansi_bright_green}}"
+yellow = "{{ansi_bright_yellow}}"
+blue = "{{ansi_bright_blue}}"
+magenta = "{{ansi_bright_purple}}"
+cyan = "{{ansi_bright_aqua}}"
+white = "{{ansi_bright_white}}"