Wayland backend: desktop icons v2, menu rebuild, layer-shell/scale fixes,

XWayland stability, GPU rendering, and multi-cursor Phase 2

The bulk of a multi-session shift's real work landed in crates/wayland.
Full root-cause/verification narrative for every item below lives in
docs/TODO.md (each has its own dated entry); this is the summary:

Desktop shell:
- Real desktop icons v2 (state/desktop_icons.rs, desktop_icons.rs):
  fixed origin-baked-before-the-bar-connects, fixed-icon sort order, and
  a proper Rename/Delete-to-Trash menu (window_memory.rs backs the
  rename-persistence side). Rubber-band marquee multi-select.
- icon_theme.rs: real freedesktop icon-theme lookup (inherits chain,
  hicolor fallback) rendering actual theme SVGs via resvg/tiny-skia,
  replacing the hand-drawn placeholder glyphs.
- Context/desktop menus (decoration.rs, desktop_menu.rs, state/menu.rs)
  rebuilt to match the project's own AGS panel styling: rounded floating
  panel, tinted-fill row highlight, real separators, a much fuller
  titlebar window-menu action set.

Layer-shell / multi-monitor:
- Layer-shell hit-testing and render positioning (input/pointer.rs,
  udev/render.rs's element placement) now correctly convert LayerMap's
  logical geometry into physical pixels on a fractionally-scaled output
  - root cause of a bottom-anchored dock being unclickable and
  unpainted while a top-anchored bar on the same output worked.
  udev/outputs.rs's relayout_outputs gained the same physical/logical
  split for cross-output positioning, now backed by a real unit test
  (next_logical_x) built from the original measured incident numbers.
- state/geometry.rs: a window's border/decoration no longer briefly
  clips when moved between differently-scaled monitors mid-drag.

XWayland / stability:
- xwayland.rs, udev/session.rs, udev/platform.rs: fixed a 100%-
  reproducible cold-start XKEYBOARD crash-loop (XWayland's own stdin
  inherited a real, already-owned VT; env passthrough and idle-callback
  spawn timing were both real, independent gaps) that had silently taken
  down all X11-app support and the global-menu registrar every session.
- state/toplevel.rs, state/lifecycle.rs: XWayland dialog detection via
  WM_TRANSIENT_FOR, not just a native xdg_toplevel parent.

Rendering:
- udev/render.rs, decoration.rs: real GPU (GBM+EGL+DrmCompositor)
  window-content and cursor rendering on the udev backend, falling back
  to the untouched Pixman path automatically on any init failure.
- decoration/tests.rs, state/mod.rs: rounded-corner/border fixes for
  interactive resize lag and cross-monitor moves.

Multi-cursor Phase 2 (virtual_pointer.rs, new; state/mod.rs, udev/
platform.rs, winit/nested_platform.rs): pins a zwlr_virtual_pointer_
unstable_v1 object to a specific window, bypassing the shared seat/
focus/pointer_pos path entirely via hand-rolled wl_pointer.enter/motion/
button/frame/leave against every WlPointer the target client has bound
(PointerHandle::client_pointers). Lets an agent operate one window while
a human uses another, genuinely simultaneously, with zero client
cooperation and no second wl_seat (confirmed a dead end: real clients
only ever bind the first seat advertised).

Full workspace build/test/clippy clean.

1 files changed, 32 insertions, 5 deletions

diff --git a/crates/wayland/src/decoration/tests.rs b/crates/wayland/src/decoration/tests.rs
index c8eb9b2..5cbc12f 100644
--- a/crates/wayland/src/decoration/tests.rs
+++ b/crates/wayland/src/decoration/tests.rs
@@ -813,14 +813,26 @@ fn context_menu_highlighted_row_has_a_different_background_than_the_rest() {
 }
 
 #[test]
-fn context_menu_border_is_opaque_at_every_edge() {
+fn context_menu_panel_is_opaque_in_the_middle_but_rounded_at_the_corners() {
+    // Reported live: the old hard-square panel with a single 1px border
+    // read as "squished... not at all polished" next to this project's own
+    // AGS reference (`GlobalMenu/style.scss`'s `popover box.menu-list`,
+    // flat rows with no border, only the panel itself rounded). A real
+    // rounded corner means the exact corner pixel is now transparent, not
+    // opaque - the opposite of what this test used to assert - while an
+    // edge's midpoint (away from any corner's curve) and the panel's own
+    // interior stay fully opaque either way.
     let items = [("Close", false)];
     let buf = render_context_menu(100, 28, &items, (0, 0, 0), (0xff, 0xff, 0xff), (0, 0, 0), (0x99, 0x99, 0x99));
     let alpha_at = |x: usize, y: usize| buf[(y * 100 + x) * 4 + 3];
-    assert_eq!(alpha_at(0, 0), 255);
-    assert_eq!(alpha_at(99, 0), 255);
-    assert_eq!(alpha_at(0, 27), 255);
-    assert_eq!(alpha_at(99, 27), 255);
+    assert_eq!(alpha_at(0, 0), 0, "the exact corner pixel is now outside the rounded curve, not a hard square");
+    // 2px in from the flat top/bottom edges, at the midpoint (far enough
+    // from either corner's own curve, and past this helper's own ~1px
+    // antialiasing band around every edge - see `fill_rounded_rect`'s
+    // shared smoothstep construction, not specific to this test).
+    assert_eq!(alpha_at(50, 2), 255, "just inside the flat top edge, away from either corner, is opaque");
+    assert_eq!(alpha_at(50, 25), 255, "just inside the flat bottom edge is opaque");
+    assert_eq!(alpha_at(50, 14), 255, "the panel's interior stays opaque");
 }
 
 #[test]
@@ -845,6 +857,21 @@ fn snap_flyout_border_is_opaque_at_every_outer_edge() {
 }
 
 #[test]
+fn render_desktop_icon_actually_draws_something_visible_for_every_kind() {
+    // Reported live: desktop icons construct and push correctly (confirmed
+    // via a live diagnostic: non-empty element list, correct position,
+    // no import error) but nothing visible shows up on screen - this
+    // isolates whether the rasterizer itself is the problem, offline,
+    // without needing a live compositor round-trip to check.
+    use crate::desktop_icons::IconKind;
+    for kind in [IconKind::Home, IconKind::Computer, IconKind::Trash, IconKind::Folder, IconKind::File] {
+        let buf = render_desktop_icon(88, 88, kind, "Test", false, (74, 144, 226), (240, 240, 240), (100, 100, 100), None);
+        let opaque_pixels = buf.chunks_exact(4).filter(|px| px[3] > 0).count();
+        assert!(opaque_pixels > 100, "{kind:?} drew only {opaque_pixels} non-transparent pixels out of {}", buf.len() / 4);
+    }
+}
+
+#[test]
 fn snap_flyout_has_an_internal_grid_line_between_columns() {
     let labels = ["A", "B", "C", "D", "E", "F"];
     let (cell_w, cell_h) = (90, 60);