breadbar: give the wifi add-network dialog proper CSD + rounded corners

Was a bare gtk4::Window with no titlebar — GTK4's own minimal CSD
fallback for that case is a flat bar with plain system-font title text
and square corners, which is what actually made this look like a stray
window from a different decade next to the rest of the (rounded,
borderless) ecosystem. Now sets a real HeaderBar (which picks up the
window's existing title automatically) and gives the dialog + headerbar
matching rounded corners and dark theming via the existing
.wifi-add-dialog CSS class.

Also switched the Connect button off "suggested-action": GTK4's bundled
theme special-cases that exact class name for a native OS-accent-colour
feature that isn't a normal CSS rule and doesn't yield to any
background-color override this stylesheet adds, confirmed empirically
(a much more specific selector had zero effect). Moved to
"confirm-button", the same accent-button convention breadman/breadpad
already use.

Known residual issue, not resolved here: the Connect button still
doesn't render the accent colour even via "confirm-button" — narrowed
down to *some* button-specific styling quirk in this one dialog (window-
level rules like the rounded corners and dark background apply
correctly; a maximally-obvious magenta test rule on the same selector
also failed to render, ruling out a color-value mistake specifically),
but not root-caused further. Left as a known follow-up rather than
blocking the CSD fix, which was the actual ask.

Also removed two `cursor: pointer` CSS properties (on .clickable and
.media-widget) that GTK4 doesn't support as a CSS property at all — was
logging "Theme parser error: No property named cursor" on every
startup, doing nothing functionally either way.

src/main.rs

@@ -1350,6 +1350,15 @@ fn show_add_network_dialog(anchor: &impl IsA<gtk4::Widget>, ssid: String, on_bui
     dialog.set_title(Some(&format!("Add “{ssid}”")));
     dialog.set_resizable(false);
     dialog.add_css_class("wifi-add-dialog");
+    // A bare gtk4::Window with no titlebar set falls back to GTK's own
+    // minimal CSD: a flat bar with plain system-font title text and no
+    // rounding — which is what actually made this look like a stray window
+    // from a different decade next to the rest of the (rounded, borderless,
+    // shadowed) ecosystem. A real HeaderBar picks up the window's own title
+    // automatically and gets the same `.wifi-add-dialog` theming below.
+    let header = gtk4::HeaderBar::new();
+    header.set_show_title_buttons(true);
+    dialog.set_titlebar(Some(&header));
     if let Some(root) = anchor.root() {
         if let Ok(win) = root.downcast::<gtk4::Window>() {
             dialog.set_transient_for(Some(&win));
@@ -1375,7 +1384,14 @@ fn show_add_network_dialog(anchor: &impl IsA<gtk4::Widget>, ssid: String, on_bui
     btn_row.set_halign(gtk4::Align::End);
     let cancel_btn = gtk4::Button::with_label("Cancel");
     let connect_btn = gtk4::Button::with_label("Connect");
-    connect_btn.add_css_class("suggested-action");
+    // Not "suggested-action" — GTK4's own bundled theme special-cases that
+    // class for a newer native OS-accent-colour feature that isn't a normal
+    // CSS rule at all, and simply doesn't lose to any `background-color`
+    // override this stylesheet adds, however specific the selector (already
+    // confirmed empirically: adding a much more specific override rule had
+    // zero effect). "confirm-button" is the same ecosystem-wide accent
+    // button convention breadman/breadpad already use successfully.
+    connect_btn.add_css_class("confirm-button");
     btn_row.append(&cancel_btn);
     btn_row.append(&connect_btn);
     body.append(&btn_row);

src/theme.rs

@@ -48,7 +48,6 @@ fn load_css() -> String {
          progressbar.osd-bar {{ min-height: 6px; }}\
          progressbar.osd-bar trough {{ background-image: none; background-color: {trough}; border-radius: 3px; min-height: 6px; }}\
          progressbar.osd-bar trough progress {{ background-image: none; background-color: {accent}; border-radius: 3px; min-height: 6px; }}\
-         .clickable {{ cursor: pointer; }}\
          .wifi-pair {{ border-radius: {radius_sm}; padding: 0 2px; }}\
          .wifi-pair:hover {{ background: alpha({on_bg}, 0.12); }}\
          .wifi-popover-inner {{ min-width: 200px; padding: {pad}; }}\
@@ -68,8 +67,14 @@ fn load_css() -> String {
          .wifi-popover-row-active {{ color: {accent}; }}\
          .wifi-popover-row-unsaved {{ opacity: 0.4; }}\
          .wifi-popover-loading {{ opacity: 0.5; padding: 8px; }}\
-         window.wifi-add-dialog {{ background-color: {bg_rgba}; color: {on_bg}; min-width: 240px; }}\
+         window.wifi-add-dialog {{ background-color: {bg_rgba}; color: {on_bg}; min-width: 240px;\
-         .media-widget {{ border-radius: {radius_sm}; padding: 0 6px; cursor: pointer; }}\
+             border-radius: {radius}; }}\
+         window.wifi-add-dialog headerbar {{ background-color: {bg_rgba}; color: {on_bg};\
+             border-top-left-radius: {radius}; border-top-right-radius: {radius};\
+             border-bottom: 1px solid alpha({on_bg}, 0.08); box-shadow: none; }}\
+         .confirm-button {{ background-color: @accent; color: @on-accent; }}\
+         .confirm-button:hover {{ background-color: alpha(@accent, 0.85); }}\
+         .media-widget {{ border-radius: {radius_sm}; padding: 0 6px; }}\
          .media-widget:hover {{ background: alpha({on_bg}, 0.10); }}\
          .media-indicator {{ font-size: 11px; opacity: 0.7; margin-right: 2px; }}\
          .media-track-lbl {{ font-size: 12px; }}\