feat(player): make native Android video the default

The two defects that were holding the flip back are fixed and verified on a
device, which is the standard this default has been held to since DR-161 shipped
a verified sub-path over an unverified one:

  - returning from background audio restarts the renderer that is actually on
    screen, instead of only ever reloading the <video> element (DR-196)
  - the letterbox bars are painted, instead of retaining whatever was last in
    the framebuffer (DR-194)

Evidence: handoff to audio-only at 69:54 returning to video playing at 70:18,
and clean bars across playback, the control bar and a rotation round-trip.

An explicit stored choice still wins in both directions, so anyone who turned the
flag off keeps it off — hence the null check on the stored value rather than a
bare === "true", which would silently re-enable it for people who opted out.

The Settings copy no longer tells users to leave it off; it now describes the
toggle as the fallback to the built-in web player.

The flag keeps its "experimental" name because it remains a suppressor of Rust's
backend choice, never a promoter: turning it on cannot produce a native backend
where Rust says HTML5.

src/lib/stores/nativeVideo.ts

@@ -50,30 +50,37 @@ const NATIVE_VIDEO_ATTR = "data-native-video";
  *
  * The picture is genuinely fixed and device-verified — `WebView transparent =
  * true` and `Marking media ready` now appear in logcat with video on screen,
- * the pair DR-172 went looking for and could not find. **The default is still
- * off**, because turning it on surfaced a different gap: the background-audio
- * handoff (UR-040) can only *return* through the HTML5 element.
- * `applyPendingForegroundSeek` bails on `!videoElement`, the HLS re-init effect
- * bails on `!useHtml5Element`, and `handleCanPlay` — the event that owns the
- * post-handoff position and play state — is an element event that never fires
- * natively. So coming back from background audio leaves playback dead.
+ * the pair DR-172 went looking for and could not find. The default nonetheless
+ * stayed **off** for a further release, because turning it on surfaced a
+ * different gap: the background-audio handoff (UR-040) could only *return*
+ * through the HTML5 element, so coming back from background audio left playback
+ * dead. That was the same shape of mistake as DR-161 — a verified sub-path
+ * shipped as a default over an unverified one — so the flip waited (DR-190).
  *
- * That is the same shape of mistake as DR-161: a verified sub-path shipped as a
- * default over an unverified one. The evidence standard this branch set for the
- * picture applies to the handoff too, so the flip waits for it (DR-190).
+ *  - **on** now. The two defects that were holding it back are fixed and
+ *    verified on a device: the handoff return restarts the renderer that is
+ *    actually on screen rather than only ever reloading the `<video>` element
+ *    (DR-196), and the letterbox bars are painted instead of retaining whatever
+ *    was last in the framebuffer (DR-194). The evidence standard this default
+ *    has been held to since DR-161 is met for both: audio handoff at 69:54
+ *    returning to video playing at 70:18, and clean bars across playback, the
+ *    control bar and a rotation round-trip.
  *
  * An explicit stored choice still wins in both directions, so anyone who turned
- * it on keeps it on.
+ * it off keeps it off — hence the `null` check rather than a bare `=== "true"`,
+ * which would silently re-enable it for people who opted out.
  *
  * TRACES: UR-003, UR-004 | DR-188
  */
 function load(): boolean {
-  if (typeof localStorage === "undefined") return false;
+  if (typeof localStorage === "undefined") return true;
   try {
-    return localStorage.getItem(STORAGE_KEY) === "true";
+    const stored = localStorage.getItem(STORAGE_KEY);
+    // Never chosen → on. Chosen → honour it, in both directions.
+    return stored === null ? true : stored === "true";
   } catch {
-    // Private-mode / disabled storage — default to the path whose handoff works.
-    return false;
+    // Private-mode / disabled storage — same default as a fresh install.
+    return true;
   }
 }
 
@@ -101,9 +108,11 @@ function createExperimentalNativeVideoStore() {
 }
 
 /**
- * User opt-in for the native Android video path. **Defaults to off** — see
- * `load()`. The name says "experimental" because the flag remains a suppressor
- * of Rust's backend choice, not a promoter of it.
+ * User preference for the native Android video path. **Defaults to on** — see
+ * `load()`. The name still says "experimental" because the flag remains a
+ * suppressor of Rust's backend choice, not a promoter of it: turning it off
+ * forces the webview element, turning it on never produces a native backend
+ * where Rust says HTML5.
  */
 export const experimentalNativeVideo = createExperimentalNativeVideoStore();