Add hot corners, media keys, orionshot, orionclip, notification history, autostart, GTK accent update, wallpaper slideshow, ISO build

- wm: hot corner polling via select()-based wm_run loop; TL=Exposé, TR=show desktop, BL=launcher, BR=lock
- wm: XF86 media key grabs (volume, brightness, playback) + Super+V for clipboard
- wm: autostart reads ~/.config/orionos/autostart on startup
- events: media key dispatch (amixer/brightnessctl/playerctl); Super+V → orionclip --show; Print → orionshot
- orionshot: new X11 screenshot tool, full-screen and rubber-band region modes, saves PNG to ~/Pictures/Screenshots/
- orionclip: new clipboard manager daemon; polls clipboard, stores 20 entries, popup via Super+V IPC
- orionnotify: append-only notification history log at ~/.local/share/orionos/notif-history.log
- themes: GTK accent updated from #3A6898 to #1E58A8 to match WM/deskbar
- themes: orionwallpaper gains --slideshow DIR [SECS] mode using feh + sleep loop
- iso: Docker-based archiso builder, live-session xinitrc, profiledef.sh
- Makefile: add orionshot and orionclip to all/clean/install; Docker-based iso target

orionshot/Makefile

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