🐛 fix(fish): check if some cli apps are installed before sourcing them

.config/fish/conf.d/atuin.fish

@@ -1,3 +1,5 @@
 if status is-interactive
-    atuin init fish | source
+    if type atuin >/dev/null ^&1
+        atuin init fish | source
+    end
 end

.config/fish/conf.d/mise.fish

@@ -1 +1,3 @@
-mise activate fish | source
+if type mise >/dev/null ^&1
+    mise activate fish | source
+end

.config/fish/conf.d/starship.fish

@@ -1 +1,3 @@
-starship init fish | source
+if type starship >/dev/null ^&1
+    starship init fish | source
+end

.config/fish/conf.d/zoxide.fish

@@ -1 +1,3 @@
-zoxide init fish | source
+if type zoxide >/dev/null ^&1
+    zoxide init fish | source
+end