feat: migrate from Zsh to Fish shell with comprehensive configuration

Major shell migration replacing Zsh/Oh-My-Zsh with Fish shell:

- Remove all Zsh configurations (dot_zshrc.tmpl, dot_p10k.zsh)
- Remove Oh-My-Zsh external dependencies from .chezmoiexternal.toml
- Add complete Fish shell setup with config.fish.tmpl and abbr.fish.tmpl
- Implement Fish-native functions for lazy-loading tools (mise, pyenv, zoxide, etc.)
- Create commonrc.fish.tmpl for cross-shell compatibility
- Add Fish plugin management via Fisher (tide prompt, fzf.fish)
- Update documentation (CLAUDE.md, TODO.md, ONBOARDING.md) to reflect Fish
- Add .fish.tmpl file association to VS Code settings
- Enhance PowerShell profile with lsd aliases
- Configure git delta pager and zdiff3 merge conflict style
- Update WSL keychain integration for Fish shell

This migration maintains all existing tool integrations while improving
startup performance through lazy-loading and Fish's native features.

home/dot_config/fish/functions/chcode.fish

@@ -0,0 +1,24 @@
+function chcode --description "Edit chezmoi files in VS Code"
+    set -gx EDITOR "code --wait"
+
+    # Check if --watch is in arguments
+    set -l has_watch false
+    set -l has_file false
+
+    for arg in $argv
+        if test "$arg" = "--watch"
+            set has_watch true
+        else if not string match -q -- '-*' $arg
+            set has_file true
+        end
+    end
+
+    # If --watch is provided but no file, show error
+    if test $has_watch = true -a $has_file = false
+        echo "--watch requires a file to be provided, directories aren't supported with watch mode"
+        return 1
+    end
+
+    # Execute chezmoi edit with all arguments
+    chezmoi edit $argv
+end