Refactor Fish shell setup in README and help.sh to use cache initialization

- Update Fish setup instructions to use a cached initialization file instead of direct command execution.
- Implement checks for the existence of the cache file before attempting to initialize, improving robustness.
- Ensure compatibility with users who have set -e in their shell configuration by adding error handling to source commands.

Author: helizaga

README.md

@@ -225,7 +225,9 @@ _gtr_init="${XDG_CACHE_HOME:-$HOME/.cache}/gtr/init-gtr.zsh"
 source "$_gtr_init" 2>/dev/null || true; unset _gtr_init
 
 # Fish (add to ~/.config/fish/config.fish)
-git gtr init fish | source
+set -l _gtr_init (test -n "$XDG_CACHE_HOME" && echo $XDG_CACHE_HOME || echo $HOME/.cache)/gtr/init-gtr.fish
+test -f "$_gtr_init"; or git gtr init fish >/dev/null 2>&1
+source "$_gtr_init" 2>/dev/null
 
 # Then navigate with:
 gtr cd                # Interactive worktree picker (requires fzf)

lib/commands/help.sh

@@ -369,7 +369,9 @@ Setup (sources cached output directly for fast startup):
   source "$_gtr_init" 2>/dev/null || true; unset _gtr_init
 
   # Fish (add to ~/.config/fish/config.fish)
-  git gtr init fish | source
+  set -l _gtr_init (test -n "$XDG_CACHE_HOME" && echo $XDG_CACHE_HOME || echo $HOME/.cache)/gtr/init-gtr.fish
+  test -f "$_gtr_init"; or git gtr init fish >/dev/null 2>&1
+  source "$_gtr_init" 2>/dev/null
 
   # Custom function name (avoids conflict with coreutils gtr)
   eval "$(git gtr init zsh --as gwtr)"