fix(clients): GTK + Decky polish batch from live Deck/Windows testing

GTK Linux client:
- hosts/library: clicking a card was dead — the handler was on
  FlowBoxChild::activate (never emitted on click); bridge child-activated
  → child.activate() on the FlowBox (ui_hosts, ui_library).
- stream: the Ctrl+Alt+Shift+D/Q/S chords (and all key forwarding) were
  dropped because the key controller sat on the overlay, which loses focus
  to the header back button after nav.push+fullscreen — move it to the
  window and remove it on teardown.
- video: a mid-session VAAPI decode error rebuilt a software decoder but
  never requested a keyframe, so under the infinite GOP the picture stayed
  gray/frozen forever. Request an IDR on any VAAPI error, keep the hardware
  decoder, and demote to software only after repeated failures.
- stream: fix a per-session Capture↔overlay reference cycle that leaked the
  overlay subtree + the Arc<NativeClient> on every session end — hold the
  overlay weakly.
- stream: accumulate the fractional wheel remainder so precision-scroll
  (Deck trackpad / hi-res wheels) sub-unit deltas aren't dropped.
- gamepad library: keep the launcher smooth on the Deck — freeze the aurora
  and trim the visible card range (fewer 3D offscreen passes) on low-power.
- gamepad: log full pad identity (vid:pid:name:type:virtual) on attach to
  diagnose an empty controller list on the Deck.
- cli: --connect host:<badport> silently did nothing; default to 9777 + warn.
- css: add the missing .pf-neutral pill rule; fix the clipped most-recent
  accent (inset outline instead of a corner-clipped box-shadow bar).

Decky plugin:
- surface the on-screen library browser: label the host-row Games button.
- fix silent pin data-loss — the detached Games modal captured a frozen
  pins array, so pinning a second game clobbered the first; mirror pins in
  a ref and track the modal's pinned ids locally for a live label.
- route pair-required hosts through the pairing modal from the fullscreen
  Stream button (parity with the QAM panel).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/decky/src/page.tsx

@@ -151,8 +151,11 @@ const HostRow: FC<{ host: Host; onPaired: () => void; onGames: () => void }> = (
         >
           <FaInfoCircle />
         </DialogButton>
-        <DialogButton style={iconButton} onClick={onGames}>
-          <FaThLarge />
+        {/* Labeled, not icon-only: this is the entry to the game picker AND the on-screen
+            library browser, and controller nav has no hover tooltip to explain a bare icon. */}
+        <DialogButton style={{ ...actionButton, minWidth: "6em" }} onClick={onGames}>
+          <FaThLarge style={{ marginRight: "0.4em" }} />
+          Games
         </DialogButton>
         {needsPair && (
           <DialogButton
@@ -162,7 +165,16 @@ const HostRow: FC<{ host: Host; onPaired: () => void; onGames: () => void }> = (
             Pair
           </DialogButton>
         )}
-        <DialogButton style={actionButton} onClick={() => startStream(host)}>
+        <DialogButton
+          style={actionButton}
+          onClick={() =>
+            needsPair
+              ? showModal(
+                  <PairModal host={host} onPaired={() => startStream(host)} />,
+                )
+              : startStream(host)
+          }
+        >
           <FaPlay style={{ marginRight: "0.4em" }} />
           Stream
         </DialogButton>