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/tab.fish

@@ -19,6 +19,14 @@
 # EXAMPLE
 #   tab
 function tab --description 'Spawn a new tab in the current terminal'
+    # Opinionated guard (C4): integrations disabled
+    if not __fish_config_op_enabled __fish_config_op_integrations
+        set -l c_err (set_color red)
+        set -l c_reset (set_color normal)
+        echo "$c_err"'tab: disabled by __fish_config_op_integrations'"$c_reset" >&2
+        return 1
+    end
+
     set -l dir "$cdto"
     if test -z "$dir"
         set dir "$PWD"