Restructure for bare Fedora: lib/ + modules/, DE selection restored

Splits setup.sh into lib/common.sh, lib/session.sh and seven modules
(3 DE, 4 TWM). Targets a bare Fedora 44+ install.

Fixes carried over from the first build:
- DEBUG_MODE was unbound under set -u, aborting the script at the version banner
- mangled 'echohttps://...' line left over from the starburst split
- set -e was missing entirely; --debug flag parsing restored
- unguarded 'clear' aborted the run without TERM
- $PRETTY_NAME unguarded under set -u
- modules were sourced, leaking shell options into the parent
- Flathub added twice (system-wide + per-user)
- no dnf5-plugins check before using 'dnf config-manager'
- no Fedora release gate
- /usr/share/xsessions assumed to exist when writing session entries

modules/twm/chadwm.sh

@@ -0,0 +1,64 @@
+#!/bin/bash
+set -uo pipefail
+
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=../../lib/common.sh
+source "$HERE/../../lib/common.sh"
+# shellcheck source=../../lib/session.sh
+source "$HERE/../../lib/session.sh"
+
+if is_debug; then set +e; else set -e; fi
+
+step "Tiling window manager: chadwm"
+rule
+
+# chadwm is an X11 dwm fork and is not packaged for Fedora anywhere. It is
+# built from source. Note this is the only non-Wayland option in the menu.
+info "Installing chadwm build dependencies..."
+install_packages \
+    gcc make git \
+    libX11-devel libXft-devel libXinerama-devel imlib2-devel \
+    dash xsetroot feh picom rofi alacritty \
+    xorg-x11-server-Xorg xorg-x11-xinit
+
+CHAD_DIR="$HOME/.config/chadwm"
+
+if [[ ! -d "$CHAD_DIR/.git" ]]; then
+    info "Cloning chadwm into $CHAD_DIR..."
+    git clone --depth 1 https://github.com/siduck/chadwm "$CHAD_DIR"
+else
+    ok "chadwm source already present at $CHAD_DIR"
+fi
+
+if [[ ! -x /usr/local/bin/chadwm ]]; then
+    info "Building and installing chadwm..."
+    # make install needs root to write /usr/local/bin
+    sudo make -C "$CHAD_DIR/chadwm" install
+else
+    ok "chadwm binary already installed."
+fi
+
+# Session wrapper: dwm forks do not do autostart themselves, so set up the
+# wallpaper/compositor here instead of leaving the user with an empty desktop.
+info "Installing session wrapper /usr/local/bin/chadwm-session..."
+sudo tee /usr/local/bin/chadwm-session >/dev/null <<'EOF'
+#!/bin/bash
+# chadwm session: compositor + wallpaper + status, then hand over to chadwm.
+pgrep -x picom >/dev/null || picom --daemon &
+if [ -d "$HOME/Pictures" ]; then
+    feh --bg-fill "$(find "$HOME/Pictures" -maxdepth 1 -type f \
+        \( -iname '*.jpg' -o -iname '*.png' \) | head -n1)" 2>/dev/null || true
+fi
+xsetroot -cursor_name left_ptr 2>/dev/null || true
+exec chadwm
+EOF
+sudo chmod 755 /usr/local/bin/chadwm-session
+
+write_x11_session chadwm "chadwm" "/usr/local/bin/chadwm-session"
+
+install_nerd_font JetBrainsMono
+
+install_packages sddm
+switch_display_manager sddm
+
+ok "chadwm setup complete. Log out and pick chadwm in SDDM."