refactor: collapse single-implementation interfaces

Nine interfaces had exactly one implementation and no test double — they existed
only to be named twice in a DI registration: IFindingsStore, IFindingsStoreLocator,
IPrimeScheduleSignal, IRefineRunner, IWeekReportService, IMergeCoordinator,
IMissionControlPane, IOnlineLoginService, ITaskListFilter. Consumers now depend on
the concrete type; the DTO records that shared those files moved next to their
implementation. IInteractiveLaunchSpecService stays — it carries 54 lines of
contract documentation, which is not ceremony.

IMergeCoordinator in particular had a redundant null object: MergeCoordinator with
a null Handler already no-ops, and every test used the real class with Handler set.

Filtering/ collapses from 8 files to 1. ITaskListFilter and TaskListFilterBase were
a double abstraction over four predicates, with MatchesAsContext => false declared
in both. SmartFlagFilter also compiled its expression twice (its own _flag plus the
inherited Matches cache) — it now uses the cache.

StaticTokenAuthProvider was in src but production uses ZitadelAuthProvider; it is
a test double, so it moves to the test project. Its own test goes away with it.

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -229,11 +229,11 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
     private readonly PlanningAggregator _planningAggregator;
     private readonly PlanningMergeOrchestrator _planningMergeOrchestrator;
     private readonly PlanningChainCoordinator _planningChain;
-    private readonly IPrimeScheduleSignal _primeSignal;
+    private readonly PrimeScheduleSignal _primeSignal;
     private readonly IPrimeRunner _primeRunner;
     private readonly ITaskStateService _state;
-    private readonly IWeekReportService _report;
-    private readonly IRefineRunner _refineRunner;
+    private readonly WeekReportService _report;
+    private readonly RefineRunner _refineRunner;
     private readonly WorkerConfig _cfg;
     private readonly OnlineInboxConfig _onlineInboxConfig;
     private readonly OnlineTokenStore _onlineTokenStore;
@@ -264,11 +264,11 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         PlanningAggregator planningAggregator,
         PlanningMergeOrchestrator planningMergeOrchestrator,
         PlanningChainCoordinator planningChain,
-        IPrimeScheduleSignal primeSignal,
+        PrimeScheduleSignal primeSignal,
         IPrimeRunner primeRunner,
         ITaskStateService state,
-        IWeekReportService report,
-        IRefineRunner refineRunner,
+        WeekReportService report,
+        RefineRunner refineRunner,
         WorkerConfig cfg,
         OnlineInboxConfig onlineInboxConfig,
         OnlineTokenStore onlineTokenStore,