feat: floating glass navigation and action bars in modals

Replace inline Save/Discard/Reset buttons with sticky glass-bubble pills
that float at the bottom of scrollable modal content. Make SpaceSettings
tab sidebar sticky with glass material. Convert RoleEditView "Back to
roles" into a sticky glass pill at the top. UserSettings Log Out + Save
always visible in a glass pill with separator. Also includes floating
position hook and popover/tooltip improvements from prior work.

packages/web/src/components/modals/spaceSettingsPanels/OverviewPanel.tsx

@@ -229,20 +229,24 @@ export function OverviewPanel({ spaceId }: OverviewPanelProps) {
           <div className="p-2 bg-status-online/10 border border-status-online/30 rounded text-status-online text-sm">Settings saved</div>
         )}
         {canManageSpace && hasChanges && (
-          <div className="flex items-center gap-2">
-            <button
-              onClick={handleSave}
-              disabled={saving || uploadingIcon || !spaceName.trim()}
-              className="px-4 py-1.5 bg-accent-primary hover:bg-accent-primary/80 text-white text-sm font-medium rounded transition-colors disabled:opacity-50"
-            >
-              {saving ? 'Saving...' : 'Save'}
-            </button>
-            <button
-              onClick={handleDiscard}
-              className="px-4 py-1.5 text-sm text-txt-tertiary hover:text-txt-secondary transition-colors"
-            >
-              Discard
-            </button>
+          <div className="sticky bottom-0 z-10 pointer-events-none">
+            <div className="flex justify-center pt-3 pb-1">
+              <div className="glass-bubble rounded-full px-4 py-2 flex items-center gap-2 animate-slide-up pointer-events-auto">
+                <button
+                  onClick={handleDiscard}
+                  className="px-3 py-1 text-sm text-txt-tertiary hover:text-txt-secondary transition-colors"
+                >
+                  Discard
+                </button>
+                <button
+                  onClick={handleSave}
+                  disabled={saving || uploadingIcon || !spaceName.trim()}
+                  className="px-3 py-1.5 bg-accent-primary hover:bg-accent-primary/80 text-white text-sm font-medium rounded-full transition-colors disabled:opacity-50"
+                >
+                  {saving ? 'Saving...' : 'Save'}
+                </button>
+              </div>
+            </div>
           </div>
         )}