feat(xtream): resume the latest series episode (#1187)

Dashboard Continue Watching now carries the exact saved season/episode into
Xtream series details and starts it at the persisted offset. Successful
external MPV/VLC launches persist the launched episode and retarget the
series CTA to "Play episode N". Recent-history rows keyed by an episode id
resolve their parent series before navigation.

Includes maintainer follow-ups: no zero-offset resume on failed position
loads, seriesXtreamId-gated resume targets for legacy rows, and patch
coverage raised from 76.7% to 93.9%.

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

docs/architecture/workspace-dashboard.md

@@ -97,6 +97,11 @@ Render rules:
        hero and cards can show progress, remaining time, and series season/
        episode badges. Series lookup uses keyed maps for both direct episode ids
        and series ids; card renders must not scan the full playback-position map.
+       Dashboard-originated Xtream series clicks also carry that exact episode
+       target through the global-recent inline-detail handoff. Once the series
+       metadata and playback positions load, the detail player consumes the
+       target once and resumes the saved episode. Opening the same item normally
+       from the global recent grid remains a detail-only action.
     3. `liveOnFavoritesCardsEnriched` — maps favorited live channels first,
        falling back to recently watched live channels when no live favorites
        exist. M3U cards carry an `epg_lookup_key` using the app-wide XMLTV
@@ -174,9 +179,12 @@ The welcome state is rendered via the existing
    rails have data.
 5. Navigation from a rail card must deep-link into the appropriate workspace
    route without switching the active playlist in the header switcher.
-6. `Recently Used Sources` reflects recent source usage across all provider
+6. Xtream series hero/Continue Watching clicks with a saved episode position
+   must resume that exact episode while preserving the collection-owned detail
+   and Back behavior. Do not apply autoplay to ordinary collection-grid clicks.
+7. `Recently Used Sources` reflects recent source usage across all provider
    types, not just recent imports.
-7. The live rail title key must match the rendered source: favorites use
+8. The live rail title key must match the rendered source: favorites use
    `WORKSPACE.DASHBOARD.LIVE_FAVORITES`; recently watched fallback uses
    `WORKSPACE.DASHBOARD.LIVE_RECENT`.