Fix spawn placement under the top bar, add per-window minimum sizes, and clean up maximize

Four reports after restarting into today's build, with a screenshot. The
screenshot was measured, not eyeballed: top bar y=0..29, a 4px accent border
at y=30..33, titlebar from y=34, bottom border at y=1027..1030, and 49px of
bare desktop below it.

Windows spawning too close to the top bar. A remembered position was
validated only by asking whether it landed on some monitor's full_geometry,
which includes the strip a top bar reserves, so an app whose remembered y was
small reopened with its titlebar under the bar. That is why it was
"sometimes": it depended on the stored value, and the live store holds
wezterm at y=44 and firefox at y=69 against a 30px bar. Remembered positions
are now clamped into the monitor's usable area.

Placement not surviving a logout. Window memory does persist, but five of the
eleven entries in the live store were saved with a second monitor attached,
at x >= 2000. Those points match no current monitor and were discarded
outright, falling back to a fresh cascade, so those apps appeared to remember
nothing. Such a position is now clamped onto a monitor that exists instead.

Per-window minimum sizes. One global floor is wrong in both directions.
Three sources now, in increasing precedence: the global floor, the client's
own declared minimum (xdg_toplevel.set_min_size or ICCCM hints), and a
min_width/min_height window rule overriding both. A rule wins permanently --
the backend refreshes the client's declared minimum on every decoration
redraw and must not undo a deliberate override.

Maximize, three faults in one report. A maximized window now draws no
border: its edges are the screen's edges, and the only place maximize stops
short is the bar strip, which is exactly where the measured line was.
maximize_geometry_for no longer subtracts a bottom-anchored dock's exclusive
zone, so maximize runs to the bottom of the screen and the dock floats over
it; top, left and right are still honoured.
general.maximize_covers_dock = false restores the old behaviour. With the
border gone the window sits flush under the bar instead of with an accent
line crowding it.

Verified: seven new tests on the real numbers from the live store, and
maximize geometry measured live in a nested instance (a window maximized on a
split half reports exactly that half's rect). NOT confirmed on screen: the
border removal and the dock behaviour - the nested backend has no bar or
dock to reserve a zone, and an attempt to check the border produced a failing
control, since srd set border_width only affects windows created after it.

515 tests pass, clippy clean.

1 files changed, 10 insertions, 1 deletions

diff --git a/crates/wayland/src/winit/render.rs b/crates/wayland/src/winit/render.rs
index ccc64a2..432ebba 100644
--- a/crates/wayland/src/winit/render.rs
+++ b/crates/wayland/src/winit/render.rs
@@ -313,7 +313,16 @@ impl WaylandPlatform {
             // doc comment further down; that's an overlap between two
             // pieces of this window's own decoration, not with its content,
             // so it doesn't contradict this paragraph.)
-            if w.border_width > 0 {
+            // No border on a maximized window. A maximized window's own
+            // edges are the screen's edges, so a border has nothing to
+            // separate it from - and where maximize *does* stop short (the
+            // strip a top bar reserves) the border lands in that gap, drawn
+            // as a hard line right against the bar. Reported live with a
+            // screenshot: a 4px accent line between the bar and the window,
+            // and none anywhere else, because the left/right/bottom strips
+            // fall off-screen. Fullscreen is already borderless for the
+            // same reason, via `decorated` being cleared.
+            if w.border_width > 0 && !w.maximized {
                 let color = crate::state::effective_border_color(w.border_color, focused == Some(id), self.wm.borrow().theme.border_inactive_dim);
                 let strips = decoration::border_strips(frame, w.border_width);
                 // Strips 0/1 (top/bottom) are rounded on their own two