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.

tests/ClaudeDo.Data.Tests/Filtering/MatchExpressionSqlTests.cs

@@ -1,11 +1,11 @@
-using ClaudeDo.Data.Filtering.Filters;
+using ClaudeDo.Data.Filtering;
 using Microsoft.EntityFrameworkCore;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
 
 namespace ClaudeDo.Data.Tests.Filtering;
 
 /// <summary>
-/// Proves that <see cref="ClaudeDo.Data.Filtering.ITaskListFilter.MatchExpression"/> is a real
+/// Proves that <see cref="ClaudeDo.Data.Filtering.TaskListFilter.MatchExpression"/> is a real
 /// expression tree that EF Core can translate into SQL, not just an in-memory delegate — the
 /// whole point of splitting it out from <c>Matches</c>.
 /// </summary>

tests/ClaudeDo.Data.Tests/Filtering/SmartFilterTests.cs

@@ -1,4 +1,4 @@
-using ClaudeDo.Data.Filtering.Filters;
+using ClaudeDo.Data.Filtering;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
 
 namespace ClaudeDo.Data.Tests.Filtering;

tests/ClaudeDo.Data.Tests/Filtering/TaskFactory.cs

@@ -1,3 +1,4 @@
+using ClaudeDo.Data.Filtering;
 using ClaudeDo.Data.Models;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
 

tests/ClaudeDo.Data.Tests/Filtering/TaskListFilterRegistryTests.cs

@@ -1,5 +1,4 @@
 using ClaudeDo.Data.Filtering;
-using ClaudeDo.Data.Filtering.Filters;
 
 namespace ClaudeDo.Data.Tests.Filtering;
 

tests/ClaudeDo.Data.Tests/Filtering/UserListFilterTests.cs

@@ -1,4 +1,4 @@
-using ClaudeDo.Data.Filtering.Filters;
+using ClaudeDo.Data.Filtering;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
 
 namespace ClaudeDo.Data.Tests.Filtering;

tests/ClaudeDo.Data.Tests/Filtering/VirtualFilterTests.cs

@@ -1,4 +1,4 @@
-using ClaudeDo.Data.Filtering.Filters;
+using ClaudeDo.Data.Filtering;
 using ClaudeDo.Data.Models;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;