cleanup: remove invented zsh override layer, harden moondoc

Earlier ClaudeCode sessions had wired a `~/.zshrc.d/*.zsh` snippet loop
plus a `~/.zshrc.local` fallback into defaults/shell/zshrc and made
post-install.sh create the directory unconditionally — neither is a zsh
convention nor documented anywhere. Remove both, simplify post-install
to write only `source /etc/zsh/zshrc.moonarch`, drop stale rustup
next-step hint, drop dead `confirm()` in lib.sh (orphan since
transform.sh deletion 2026-04-21).

moonarch-doctor: replace useless existence checks (zshrc.moonarch,
/usr/share/moonarch/) with real signal. User-service and helper-script
lists now derive from `pacman -Qql moonarch-git` (drift-proof) plus an
explicit list of post-install-enabled externals (currently `stasis`).
New udev-effectiveness check for charge_control_end_threshold —
verifies group=wheel + group-writable, surfaces broken rules instead
of staying silent.

Translate two German ABOUTME comments (moonarch-waybar-cpugov,
moonarch-waybar-gpustat) to English for consistency.

scripts/post-install.sh

@@ -114,9 +114,7 @@ gsettings set org.gnome.desktop.interface font-name 'UbuntuSans Nerd Font 11'
 
 if [[ ! -f "$HOME/.zshrc" ]]; then
     log "No ~/.zshrc found — sourcing Moonarch defaults."
-    mkdir -p "$HOME/.zshrc.d"
-    echo "# Load Moonarch defaults, add custom overrides in ~/.zshrc.d/ or below" > "$HOME/.zshrc"
-    echo "source /etc/zsh/zshrc.moonarch" >> "$HOME/.zshrc"
+    echo "source /etc/zsh/zshrc.moonarch" > "$HOME/.zshrc"
 fi
 
 # --- Seed Stasis user config ---
@@ -210,6 +208,5 @@ log ""
 log "Next steps:"
 log "  1. Reboot"
 log "  2. Place wallpapers in ~/Pictures/Wallpaper/"
-log "  3. rustup default stable"
-log "  4. User overrides in ~/.config/ or ~/.zshrc.d/"
+log "  3. User overrides in ~/.config/"
 log ""