feat(quest): QT6 — plugins can read the contract tracker

The last piece of QT6's own scope: r10-quest-dialogs.md §11.6's contract half.
IGameState.Contracts exposes what the client structurally knows about quests,
which — per that same research — is the tracker and nothing else. The rest of
§11.6 (chat stream, tells, give, use, confirmations) is other features and
stays out of this campaign.

A pull-through source rather than a pushed mirror. Contracts change rarely and
are already owned canonically, so a second copy would only be a thing to keep
in step; reading through means a plugin cannot observe a stale list.

Both hosts implement it. The headless one carries contract id, stage and
progress but no names — a bot has no dat access — because losing the TEXT is
expected while losing the QUEST would leave a bot silently unable to see what
it is on. Same rule covers a contract the installed dat has never heard of: it
still projects, with empty text and a correct status, rather than vanishing.

The interface member is defaulted so a host predating this campaign still
satisfies IGameState.

Two lazy catalog loads exist (the panel's and this one) rather than one shared
instance. That is deliberate: threading a shared ContractCatalog through three
composition records to avoid reading a 322-row immutable table at most twice
per session would be plumbing for no correctness or performance gain, and the
comment at the call site says so.

Campaign QT is complete; the connected user gate is owed.

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

src/AcDream.App/Composition/SessionPlayerComposition.cs

@@ -278,6 +278,30 @@ internal sealed class SessionPlayerCompositionPhase
             d.DatLock,
             world.TerrainBuild.HeightTable,
             d.Options.DumpSceneryZ);
+        // Campaign QT slice QT6: the plugin-facing contract view. A
+        // pull-through source rather than a mirror, so a plugin always reads
+        // the canonical tracker instead of a copy that could fall behind it.
+        //
+        // The catalog is loaded lazily and independently of the Journal
+        // panel's own. Two reads of a 322-row immutable table across a whole
+        // session is not worth threading a shared instance through three
+        // composition records for; correctness is identical either way.
+        AcDream.Core.Quests.ContractCatalog? pluginContractCatalog = null;
+        d.WorldGameState.ContractsSource = () =>
+        {
+            if (pluginContractCatalog is null)
+            {
+                lock (d.DatLock)
+                    pluginContractCatalog =
+                        AcDream.Content.ContractTableReader.Load(content.Dats);
+            }
+
+            return AcDream.Runtime.Gameplay.ContractPluginProjection.Project(
+                d.Runtime.ContractsOwner.View,
+                pluginContractCatalog,
+                DateTime.UtcNow);
+        };
+
         var streamerLease = scope.Acquire(
             "landblock streamer",
             () => LandblockStreamer.CreateForRequests(