fix: player bar CSS + Windows media keys HWND (v1.17.2)

- layout: overflow:hidden on .app-shell + min-height:0 on sidebar/main/queue
  prevents player bar from being pushed off-screen when window is resized
  below OS minHeight constraint (ignored by some Linux WMs)
- lib.rs: pass main window HWND to souvlaki PlatformConfig on Windows so
  SMTC hooks into the existing Win32 message loop instead of creating its
  own — fixes media keys on Windows without crashing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/styles/layout.css

@@ -9,6 +9,12 @@
     "sidebar main queue"
     "player  player player";
   height: 100vh;
+  /* overflow: hidden keeps the player bar pinned at the bottom even when the
+     window is dragged below the OS minHeight constraint (ignored on some
+     Linux WMs/compositors). Without this, the 1fr row's implicit auto
+     min-height can push the grid taller than 100vh, scrolling the player
+     bar out of view. */
+  overflow: hidden;
   background: var(--bg-app);
 }
 
@@ -39,6 +45,7 @@
   border-right: 1px solid var(--border-subtle);
   position: relative;
   z-index: 2;
+  min-height: 0; /* allow 1fr row to shrink freely */
 }
 
 .sidebar-brand {
@@ -301,6 +308,7 @@
   flex-direction: column;
   overflow: hidden;
   min-width: 0;
+  min-height: 0; /* allow 1fr row to shrink freely */
   background: var(--bg-app);
   z-index: 1;
 }
@@ -635,6 +643,7 @@
   flex-direction: column;
   overflow: hidden;
   min-width: 0;
+  min-height: 0; /* allow 1fr row to shrink freely */
 }
 
 .queue-header {