feat(truth): schema_version 2 read path, v2 only

Replaces the v1 shape rather than accepting both. `anneal_sec` and the
top-level `sample_fps` are deleted, not zeroed; `extraction` and `cut`
blocks arrive; `scenes` become objects carrying belief and route, so a
window records how far to trust it instead of being a bare float pair.

`TruthSchema.IsSupported` is the single gate and is applied on all four
read paths — sidecar, managed store load, managed PUT, and converted
manifest. Previously only the controller checked, so the version the
plugin claimed to require and the one it would actually parse were free
to drift. Rejections name the file and the version found, so an item that
looks empty is distinguishable from one that was refused.

`ManifestConverter` carries belief, route and both provenance blocks
through: dropping them would silently downgrade every fetched manifest
against a locally extracted one.

TRACES: JR-002, JR-003 | SR-003

Jellyfin.Plugin.JRay/Services/PresenceLookup.cs

@@ -48,7 +48,7 @@ public static class PresenceLookup
         // scale (see JR-006).
         foreach (var window in actor.Scenes)
         {
-            if (window.Length == 2 && window[0] <= t && t <= window[1])
+            if (window is not null && window.Start <= t && t <= window.End)
             {
                 return true;
             }
@@ -101,17 +101,17 @@ public static class PresenceLookup
         double previousStart = double.NegativeInfinity;
         foreach (var window in actor.Scenes)
         {
-            if (window.Length != 2)
+            if (window is null)
             {
                 continue;
             }
 
-            if (window[0] < previousStart)
+            if (window.Start < previousStart)
             {
                 return false;
             }
 
-            previousStart = window[0];
+            previousStart = window.Start;
         }
 
         return true;