feat(guards): add in-function opinionated guards and CachyOS cleanup

C1 shadows (rm, cat, ls, less, du, bash, top, ping, ssh, rg, mkdir,
help) fall back to the bare command when __fish_config_op_aliases is
falsy; rm falls back to exact 'command rm' with no wrapper. C2 gates
the auto-venv PWD hook. C3 gates smart_exit (composing with Task #4
logging), fish_right_prompt, and all six expand_bang_*/expand_typo_sub
functions atomically with the bang-bang system. C4 integration commands
(spwin, tab, split, hist, logs, upgrade) refuse with a colored stderr
error when disabled. config.fish now also strips the CachyOS distro
config's own bang-bang bindings, history override, and alias opinions
per category, restoring fish stock functions where they exist.

functions/mkdir.fish

@@ -16,6 +16,12 @@
 # EXAMPLE
 #   mkdir ~/projects/myapp/src
 function mkdir --description 'Execute mkdir'
+    # Opinionated guard (C1): fall back to bare command mkdir when disabled.
+    if not __fish_config_op_enabled __fish_config_op_aliases
+        command mkdir $argv
+        return $status
+    end
+
     if status is-interactive
         # Fall back to command mkdir -p when flags are present (e.g. -m 755)
         for _arg in $argv