feat: add chezmoi merge tools with VSCode integration and Fish helper

- Add VSCode-based merge helper with clear visual layout explanation
- Add Fish function for fzf-based interactive conflict selection
- Update CLAUDE.md with .tmpl file search patterns and tool usage guidelines

home/dot_local/bin/executable_chezmoi-merge-helper.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# Helper script for chezmoi merge with clear labels
+# Arguments: $1=destination $2=target $3=source
+
+destination="$1"
+target="$2"
+source="$3"
+
+# Create base file (copy of target state)
+base="${target}.base"
+cp "$target" "$base"
+
+# Show clear explanation before merge
+cat << EOF
+╔════════════════════════════════════════════════════════════════╗
+║                    CHEZMOI MERGE LAYOUT                        ║
+╠════════════════════════════════════════════════════════════════╣
+║                                                                ║
+║  LEFT (Current):    DESTINATION - File in your home dir       ║
+║                     ↓ External changes (e.g., app updates)    ║
+║                                                                ║
+║  RIGHT (Incoming):  TARGET - What chezmoi wants to apply      ║
+║                     ↓ Your chezmoi changes (templates, etc)   ║
+║                                                                ║
+║  BOTTOM (Result):   SOURCE - Will be saved to chezmoi repo    ║
+║                                                                ║
+╠════════════════════════════════════════════════════════════════╣
+║  File: $(basename "$destination")
+╚════════════════════════════════════════════════════════════════╝
+
+Press Enter to open merge editor...
+EOF
+
+read -r
+
+# Launch VSCode merge
+# Syntax: code --merge <current> <incoming> <base> <result>
+code --new-window --wait --merge "$destination" "$target" "$base" "$source"
+
+# Cleanup
+rm -f "$base"