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

orionnotify/orionnotify.c

@@ -12,6 +12,7 @@
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
+#include <sys/stat.h>
 
 #define DESKBAR_W    200
 #define NOTIF_W      320
@@ -124,6 +125,26 @@ static void notif_close(int idx) {
     notif_restack();
 }
 
+static void notif_log(const char *summary, const char *body) {
+    const char *home = getenv("HOME");
+    if (!home) return;
+    char dir[512], path[560];
+    snprintf(dir,  sizeof(dir),  "%s/.local/share/orionos", home);
+    snprintf(path, sizeof(path), "%s/notif-history.log", dir);
+    mkdir(dir, 0755);
+    FILE *f = fopen(path, "a");
+    if (!f) return;
+    time_t t = time(NULL);
+    /* sanitise: replace tabs and newlines with spaces */
+    char sum[128], bod[256];
+    strncpy(sum, summary ? summary : "", 127); sum[127] = '\0';
+    strncpy(bod, body    ? body    : "", 255); bod[255] = '\0';
+    for (char *p = sum; *p; p++) if (*p == '\t' || *p == '\n') *p = ' ';
+    for (char *p = bod; *p; p++) if (*p == '\t' || *p == '\n') *p = ' ';
+    fprintf(f, "%ld\t%s\t%s\n", (long)t, sum, bod);
+    fclose(f);
+}
+
 static unsigned int notif_add(const char *summary, const char *body, int expire_ms) {
     if (n_notifs >= NOTIF_MAX) {
         /* evict oldest */
@@ -145,6 +166,7 @@ static unsigned int notif_add(const char *summary, const char *body, int expire_
     clock_gettime(CLOCK_MONOTONIC, &n->show_time);
     n->active = 1;
     n_notifs++;
+    notif_log(summary, body);
 
     int nx = notif_x();
     int ny = notif_y(n_notifs - 1);