feat(#109): implement PiP close_button on Android (was a documented no-op)

The server forwarded close_button (routes/pip.js) and it's in openapi.yaml, but
no player rendered it — Tizen deferred "close-button focus" as non-MVP, the web
player has none, and Android's PipOverlay never read the flag. So the documented
field did nothing on any device.

Implement it on Android: when close_button:true, a tappable ✕ floats at the box's
top-right in a FrameLayout wrapper that is a SIBLING of the box — so it isn't
clipped by the box outline or dimmed by the overlay opacity. Tapping it clears
THIS overlay (id-matched via the captured token). Only the ✕ is clickable; the
rest of the full-screen pipLayout stays touch-transparent, so taps elsewhere
fall through to the playing content (no input regression).

Verified on the emulator over live YouTube: the ✕ renders at the corner, and
tapping it removes the overlay while the video keeps playing.

Parity note: web/Tizen players still don't implement close_button; D-pad focus
of the ✕ on non-touch TV hardware is intentionally not wired (MVP = touch/pointer,
matching the Tizen focus deferral).

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

android/app/src/main/java/com/remotedisplay/player/player/PipOverlay.kt

@@ -134,7 +134,36 @@ class PipOverlay(
                 else -> { lp.rightMargin = mx; lp.topMargin = my; Gravity.TOP or Gravity.END } // top-right
             }
 
-            pipLayout.addView(box, lp)
+            // Optional close button (close_button:true). Render a tappable ✕ floating at the
+            // box's top-right corner; tapping clears THIS overlay (id-matched). It lives in a
+            // FrameLayout wrapper that is a SIBLING of the box — so it isn't clipped by the
+            // box outline and isn't dimmed by the box's opacity. Only the button is clickable;
+            // the rest of pipLayout stays touch-transparent so taps fall through to content.
+            val attach: View = if (p.optBoolean("close_button", false)) {
+                val token = current
+                FrameLayout(context).apply {
+                    addView(box, FrameLayout.LayoutParams(
+                        FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT))
+                    val d = dm.density
+                    addView(TextView(context).apply {
+                        text = "✕" // ✕
+                        setTextColor(Color.WHITE)
+                        textSize = 16f
+                        gravity = Gravity.CENTER
+                        background = GradientDrawable().apply {
+                            shape = GradientDrawable.OVAL; setColor(Color.argb(150, 0, 0, 0))
+                        }
+                        isClickable = true
+                        contentDescription = "Close"
+                        setOnClickListener { clear(token) }
+                    }, FrameLayout.LayoutParams((28 * d).toInt(), (28 * d).toInt()).apply {
+                        gravity = Gravity.TOP or Gravity.END
+                        val m = (6 * d).toInt(); topMargin = m; rightMargin = m
+                    })
+                }
+            } else box
+
+            pipLayout.addView(attach, lp)
             pipLayout.visibility = View.VISIBLE
             // current was set above (before media build) so loadImageInto's token matches.
 

docs/109-android-pip-visibility.md

@@ -162,6 +162,17 @@ over both a static image and live YouTube.
   needed — web PiPs never went through the broken image path.
 - title + `background_color` box — paints above the video (the original cause-1
   fix).
+- **`close_button: true`** — the server already forwarded this flag
+  (`routes/pip.js`) and it's in `openapi.yaml`, but no player rendered it (Tizen
+  deferred "close-button focus" as non-MVP; the web player has none). Implemented
+  on Android: a tappable ✕ floats at the box's top-right (a sibling of the box, so
+  it isn't clipped by the outline or dimmed by `opacity`) and clears THIS overlay
+  (id-matched) on tap. Only the ✕ is clickable; the rest of the full-screen
+  `pipLayout` stays touch-transparent so taps fall through to the content. Verified
+  on the emulator — tapping it removed the overlay and the video kept playing.
+  Parity note: the web/Tizen players still don't implement `close_button`; D-pad
+  focus of the ✕ on non-touch TV hardware is intentionally not wired (MVP =
+  touch/pointer only, matching the Tizen focus deferral).
 
 ## If the magenta box is STILL hidden over YouTube on the test device