feat(playback): show media title overlay in fullscreen shared controls (#1228)

* feat(playback): show media title overlay in fullscreen shared controls

In fullscreen with the shared player-controls layer, a pointer-transparent
overlay at the top of the player now names the content while controls are
revealed: one line for movies and live channels, two lines for series
(series name + S01E03 label). The overlay follows the bar's auto-hide
transition and stays hidden outside fullscreen, where page chrome already
names the content.

Data flows top-down: the Xtream/Stalker series detail views pass the series
name via a new PortalInlinePlayerComponent.seriesTitle input (Xtream episode
playback titles carry the episode name, not the series), the inline player
builds the two-line form from the episode metadata label, and
WebPlayerViewComponent falls back to playback.title for movies/channels
while skipping raw stream-URL fallbacks. All four shared-controls hosts
(HTML5, Video.js, ArtPlayer, Embedded MPV frame-copy) forward the value.

To stay under the max-lines limit, scrub/timeline state is extracted into
ControlsTimeline and the playback-diagnostics display helpers into
web-player-view-diagnostics.utils.ts, with behavior unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* docs: mirror fullscreen media-title contract into AGENTS.md

Addresses Codex review: the Shared Player Controls section in AGENTS.md
must stay in sync with the CLAUDE.md description of the new mediaTitle
input, fullscreen overlay behavior, and series-title wiring.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

docs/architecture/player-controls-contract.md

@@ -225,9 +225,29 @@ It owns only transient presentation behavior:
 - `ControlsVolume` — persisted/optimistic volume state reconciled from
   controller state;
 - `ControlsShortcuts` — document keyboard routing;
-- `ControlsSurface` — pointer/click/double-click surface interactions; and
+- `ControlsSurface` — pointer/click/double-click surface interactions;
+- `ControlsTimeline` — scrub state and timeline projections; and
 - `controls-view-model.ts` — derived display state.
 
+### Fullscreen media title
+
+The component accepts an optional `mediaTitle` input
+(`PlayerMediaTitle { primary, secondary? }`) with display-ready strings — the
+movie title, channel name, or series name, plus an optional second line such
+as the `S01E03` episode label. The overlay renders at the top of the player
+only in fullscreen while the controls are revealed, follows the same
+auto-hide transition as the bottom bar, and is pointer-transparent. Outside
+fullscreen the surrounding page chrome already names the content, so the
+overlay stays hidden.
+
+Hosts supply the value: `WebPlayerViewComponent` derives a single-line title
+from the resolved playback (skipping raw stream-URL fallbacks) unless its own
+`mediaTitle` input was set, and `PortalInlinePlayerComponent` builds the
+two-line series form from its `seriesTitle` input plus the episode metadata
+label. The Xtream and Stalker series detail views pass the series name via
+`seriesTitle`; movie and live hosts need no extra wiring because
+`playback.title` already names the content.
+
 ### Keyboard ownership
 
 Unmodified Space/K, F, arrow keys, and M are playback shortcuts. Playback keys