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/__auto_source_fallback_venv.fish

@@ -14,7 +14,10 @@
 #   cd ~/myproject  # activates .venv if present
 function __auto_source_fallback_venv --on-variable PWD
     status --is-command-substitution; and return
-    
+
+    # Opinionated guard (C2): no automatic venv activation when disabled.
+    __fish_config_op_enabled __fish_config_op_autoexec; or return
+
     # 1. Skip if direnv is already managing this directory
     if set -q DIRENV_DIR; or test -e ".envrc"
         return