feat: enhance install script and theme generation

- install.sh now installs all variants when run without parameters
- preserve single-variant mode when --variant is specified
- add variant names to generated file headers for clarity
- fix tool name extraction to preserve compound names like git-delta
- fix CSS variable preservation during header generation

cli/zsh/everforest-dark-hard.zsh

@@ -1,4 +1,4 @@
-# Everforest theme for Zsh
+# Everforest dark-hard theme for Zsh
 # Add this to your ~/.zshrc
 
 # Everforest color scheme for Zsh syntax highlighting and prompt

cli/zsh/everforest-dark-medium.zsh

@@ -1,4 +1,4 @@
-# Everforest theme for Zsh
+# Everforest dark-medium theme for Zsh
 # Add this to your ~/.zshrc
 
 # Everforest color scheme for Zsh syntax highlighting and prompt

cli/zsh/everforest-dark-soft.zsh

@@ -1,4 +1,4 @@
-# Everforest theme for Zsh
+# Everforest dark-soft theme for Zsh
 # Add this to your ~/.zshrc
 
 # Everforest color scheme for Zsh syntax highlighting and prompt

cli/zsh/everforest-light-hard.zsh

@@ -1,4 +1,4 @@
-# Everforest theme for Zsh
+# Everforest light-hard theme for Zsh
 # Add this to your ~/.zshrc
 
 # Everforest color scheme for Zsh syntax highlighting and prompt

cli/zsh/everforest-light-medium.zsh

@@ -1,4 +1,4 @@
-# Everforest theme for Zsh
+# Everforest light-medium theme for Zsh
 # Add this to your ~/.zshrc
 
 # Everforest color scheme for Zsh syntax highlighting and prompt

cli/zsh/everforest-light-soft.zsh

@@ -1,4 +1,4 @@
-# Everforest theme for Zsh
+# Everforest light-soft theme for Zsh
 # Add this to your ~/.zshrc
 
 # Everforest color scheme for Zsh syntax highlighting and prompt