feat(fws-about): add fws-about dialog application for system information

Add a new GTK3-based Python application that displays an "About FWS" dialog with two tabs:

- "Le projet FWS" tab: shows project name, description, features, and home URL
- "Système" tab: displays system information including OS, kernel, desktop environment, hardware (CPU, memory, GPUs, disks)

The application detects system information from /proc, lsblk, lspci, and environment variables. It replaces the default Xfce About dialog with FWS branding.

configs/releng/airootfs/usr/local/bin/fws-about

@@ -0,0 +1,185 @@
+#!/usr/bin/env python3
+# FWS — fenêtre « À propos » : deux onglets, « Le projet FWS » (ce qu'est FWS,
+# version, liens) et « Système » (matériel + logiciel détectés). Remplace le
+# « About Xfce » de libxfce4ui par une page de marque FWS. GTK3 (python-gobject
+# installé avec le bureau).
+
+import os
+import re
+import subprocess
+
+import gi
+
+gi.require_version("Gtk", "3.0")
+gi.require_version("Gdk", "3.0")  # sinon gi charge Gdk 4.0 (conflit avec Gtk3)
+from gi.repository import Gdk, GLib, Gtk  # noqa: E402
+
+GLib.set_prgname("fws-about")
+
+
+def _osrelease():
+    data = {}
+    for path in ("/etc/os-release", "/usr/lib/os-release"):
+        try:
+            with open(path) as fh:
+                for line in fh:
+                    m = re.match(r'^([A-Z_]+)=(.*)$', line.strip())
+                    if m:
+                        data[m.group(1)] = m.group(2).strip('"')
+            break
+        except OSError:
+            continue
+    return data
+
+
+def _cmd(*argv):
+    try:
+        return subprocess.check_output(argv, text=True,
+                                       stderr=subprocess.DEVNULL).strip()
+    except (OSError, subprocess.CalledProcessError):
+        return ""
+
+
+def _cpu():
+    try:
+        with open("/proc/cpuinfo") as fh:
+            for line in fh:
+                if line.startswith("model name"):
+                    return line.split(":", 1)[1].strip()
+    except OSError:
+        pass
+    return "inconnu"
+
+
+def _mem():
+    try:
+        with open("/proc/meminfo") as fh:
+            for line in fh:
+                if line.startswith("MemTotal"):
+                    kib = int(line.split()[1])
+                    return f"{kib / 1048576:.1f} Gio"
+    except OSError:
+        pass
+    return "inconnu"
+
+
+def _gpus():
+    out = []
+    for line in _cmd("lspci").splitlines():
+        low = line.lower()
+        if "vga" in low or "3d" in low or "display" in low:
+            out.append(line.split(":", 2)[-1].strip())
+    return out or ["inconnu"]
+
+
+def _desktop():
+    if os.environ.get("HYPRLAND_INSTANCE_SIGNATURE"):
+        return "Hyprland"
+    env = os.environ.get("XDG_CURRENT_DESKTOP") \
+        or os.environ.get("DESKTOP_SESSION") or ""
+    return env or "inconnu"
+
+
+def _session_type():
+    t = os.environ.get("XDG_SESSION_TYPE", "")
+    return {"wayland": "Wayland", "x11": "X11"}.get(t, t or "inconnu")
+
+
+def _disks():
+    out = []
+    for line in _cmd("lsblk", "-dno", "NAME,SIZE,MODEL,TYPE").splitlines():
+        f = line.split()
+        if f and f[-1] == "disk":
+            out.append(" ".join(f[:-1]))
+    return out or ["inconnu"]
+
+
+def _grid(rows):
+    grid = Gtk.Grid(column_spacing=18, row_spacing=8, margin=18)
+    for i, (key, val) in enumerate(rows):
+        k = Gtk.Label(xalign=1)
+        k.set_markup(f"<b>{GLib.markup_escape_text(key)}</b>")
+        k.get_style_context().add_class("dim-label")
+        v = Gtk.Label(label=val, xalign=0, selectable=True)
+        v.set_line_wrap(True)
+        grid.attach(k, 0, i, 1, 1)
+        grid.attach(v, 1, i, 1, 1)
+    return grid
+
+
+def _project_tab(osr):
+    box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=10, margin=20)
+    title = Gtk.Label()
+    name = osr.get("PRETTY_NAME") or osr.get("NAME") or "FWS Linux"
+    title.set_markup(f"<span size='xx-large' weight='bold'>{name}</span>")
+    box.pack_start(title, False, False, 0)
+
+    tag = Gtk.Label(label="Une distribution Arch Linux pensée pour remplacer "
+                          "Windows : bureau prêt à l'emploi, jeux, VR et "
+                          "compatibilité applicative.")
+    tag.set_line_wrap(True)
+    tag.set_max_width_chars(52)
+    box.pack_start(tag, False, False, 0)
+
+    feats = Gtk.Label()
+    feats.set_markup(
+        "<b>Inclus :</b>  installateur graphique · plusieurs bureaux "
+        "(GNOME, KDE, Hyprland, i3, XFCE) · Steam &amp; Proton-GE · "
+        "réalité virtuelle (SteamVR) · winboat (applications Windows) · "
+        "pare-feu · réparation système intégrée.")
+    feats.set_line_wrap(True)
+    feats.set_max_width_chars(52)
+    feats.set_xalign(0)
+    box.pack_start(feats, False, False, 6)
+
+    home = osr.get("HOME_URL") or "https://github.com/You-re-like-Windows-a-bitch/fws"
+    link = Gtk.LinkButton.new_with_label(home, "Site du projet")
+    box.pack_start(link, False, False, 0)
+    return box
+
+
+def _system_tab(osr):
+    rows = [
+        ("Système", osr.get("PRETTY_NAME", "FWS Linux")),
+        ("Build", osr.get("BUILD_ID", "rolling")),
+        ("Noyau", _cmd("uname", "-r") or "inconnu"),
+        ("Bureau", _desktop()),
+        ("Affichage", _session_type()),
+        ("Nom de machine", _cmd("hostname") or os.uname().nodename),
+        ("Processeur", _cpu()),
+        ("Mémoire", _mem()),
+        ("Carte(s) graphique(s)", "\n".join(_gpus())),
+        ("Disque(s)", "\n".join(_disks())),
+    ]
+    scroll = Gtk.ScrolledWindow()
+    scroll.set_policy(Gtk.PolicyType.NEVER, Gtk.PolicyType.AUTOMATIC)
+    scroll.add(_grid(rows))
+    return scroll
+
+
+class AboutWindow(Gtk.Window):
+    def __init__(self):
+        super().__init__(title="À propos de FWS")
+        self.set_default_size(520, 460)
+        self.set_position(Gtk.WindowPosition.CENTER)
+        self.set_type_hint(Gdk.WindowTypeHint.DIALOG)
+
+        osr = _osrelease()
+        notebook = Gtk.Notebook()
+        notebook.append_page(_project_tab(osr), Gtk.Label(label="Le projet FWS"))
+        notebook.append_page(_system_tab(osr), Gtk.Label(label="Système"))
+        self.add(notebook)
+        self.connect("destroy", Gtk.main_quit)
+
+
+def main():
+    if not Gtk.init_check()[0]:
+        return 1
+    win = AboutWindow()
+    win.show_all()
+    Gtk.main()
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())