Reorganize configuration into modular directory structure

- Create modules/ directory for Nix configuration modules
- Create config/ directory for configuration files
- Move nvim.nix, tmux.nix, zsh.nix to modules/
- Move p10k.zsh to config/
- Update flake.nix import paths to reference new structure
- Update zsh.nix p10k.zsh path reference
- Update README.md architecture documentation
- Keep tmux.sh at root for easy accessibility

This provides better separation between Nix modules and config files
while maintaining a clean, scalable structure.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

modules/zsh.nix

@@ -0,0 +1,98 @@
+{ pkgs, ... }:
+
+{
+  programs.zsh = {
+    enable = true;
+    defaultKeymap = "viins";
+    enableVteIntegration = true;
+    enableCompletion = true;
+    autosuggestion.enable = true;
+    syntaxHighlighting.enable = true;
+    
+    sessionVariables = {
+      COLORTERM = "truecolor";
+      EDITOR = "nvim";
+    };
+    
+    shellAliases = {
+      ll = "ls -alF";
+      la = "ls -A";
+      l = "ls -CF";
+      ".." = "cd ..";
+      "..." = "cd ../..";
+      
+      # Git aliases
+      gs = "git status";
+      ga = "git add";
+      gc = "git commit";
+      gp = "git push";
+      gl = "git pull";
+      gd = "git diff";
+      
+      # Nix helpers
+      hm = "home-manager";
+      hms = "home-manager switch --flake ~/.config/nix#yanlin";
+    };
+    
+    initContent = ''
+      # Load Powerlevel10k theme
+      if [[ -f ${pkgs.zsh-powerlevel10k}/share/zsh-powerlevel10k/powerlevel10k.zsh-theme ]]; then
+        source ${pkgs.zsh-powerlevel10k}/share/zsh-powerlevel10k/powerlevel10k.zsh-theme
+      fi
+      
+      # Load Powerlevel10k configuration (managed by Nix)
+      source ~/.p10k.zsh
+      
+      # Vim mode configuration
+      # Reduce delay when switching modes (10ms instead of 400ms)
+      export KEYTIMEOUT=1
+      
+      # Cursor shape changes for vim modes
+      function zle-keymap-select {
+        case $KEYMAP in
+          vicmd)      echo -ne '\e[1 q';;  # block cursor for normal mode
+          viins|main) echo -ne '\e[5 q';;  # line cursor for insert mode
+        esac
+      }
+      zle -N zle-keymap-select
+      
+      # Ensure we start with line cursor in insert mode
+      function zle-line-init {
+        echo -ne '\e[5 q'
+      }
+      zle -N zle-line-init
+      
+      # Fix cursor after each command
+      function preexec {
+        echo -ne '\e[5 q'
+      }
+      
+      # Additional vim-like bindings
+      bindkey -M vicmd 'k' history-search-backward
+      bindkey -M vicmd 'j' history-search-forward
+      bindkey -M vicmd '/' history-incremental-search-backward
+      bindkey -M vicmd '?' history-incremental-search-forward
+      
+      # Better word movement in insert mode
+      bindkey '^[[1;5C' forward-word      # Ctrl+Right
+      bindkey '^[[1;5D' backward-word     # Ctrl+Left
+    '';
+  };
+  
+  # Essential packages for enhanced zsh experience
+  home.packages = with pkgs; [
+    zsh-powerlevel10k
+    fzf
+    fd
+    ripgrep
+    bat
+  ];
+  
+  programs.fzf = {
+    enable = true;
+    enableZshIntegration = true;
+  };
+  
+  # Manage Powerlevel10k configuration
+  home.file.".p10k.zsh".source = ../config/p10k.zsh;
+}