Add 6 desktop features: workspace shortcuts, Exposé, deskbar icons, notifications, screen lock, move-to-desktop

- Super+1-4: switch virtual desktop; Super+Shift+1-4: move focused window to desktop N
- Super+Space: Exposé window overview (tiled grid), click to select, Escape to cancel
- wm/src/expose.c: expose_show/expose_hide using ceil(sqrt) grid layout with saved/restored geometry
- client_move_to_desktop(): moves window between desktops, fires _NET_WM_DESKTOP update
- on_client_message: handles _NET_WM_DESKTOP to move windows from external requests
- deskbar: optional imlib2 app icon rendering (Papirus-Dark → Papirus → hicolor → pixmaps fallback)
- deskbar: XGetClassHint populates cls field for better icon lookup
- deskbar: context menu extended with separator + "→ Desktop 1-4" items via _NET_WM_DESKTOP
- orionnotify/: freedesktop.org notification daemon (libdbus-1), stacks up to 5 popups top-right
- orionlock/: PAM-authenticated fullscreen screen lock with clock, date, password dots
- Lock Screen menu item wired to orionlock
- Root Makefile includes orionnotify and orionlock targets

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GHiBQKPfUoaJgCKuA9op1H

orionnotify/Makefile

@@ -0,0 +1,22 @@
+CC = gcc
+
+PKG_C := $(shell pkg-config --cflags dbus-1 xft x11 2>/dev/null)
+PKG_L := $(shell pkg-config --libs   dbus-1 xft x11 2>/dev/null)
+
+ifeq ($(PKG_C),)
+  $(error "Required: libdbus-1-dev libxft-dev libx11-dev")
+endif
+
+CFLAGS  = -Wall -Wextra -O2 $(PKG_C)
+LDFLAGS = $(PKG_L)
+
+BIN = orionnotify
+
+.PHONY: all clean install
+all: $(BIN)
+$(BIN): orionnotify.c
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+install: $(BIN)
+	install -Dm755 $(BIN) /usr/local/bin/$(BIN)
+clean:
+	rm -f $(BIN)