perf(ui): push task-list filtering into SQL

LoadForListAsync loaded the entire tasks table (all lists, two Include
joins) then filtered to the selected list in C#, never using
idx_tasks_list_id/idx_tasks_status. ITaskListFilter now exposes
MatchExpression, an Expression<Func<TaskEntity,bool>> that EF Core can
translate to SQL; a new TaskListFilterBase compiles it on demand for the
existing in-memory Matches(). The primary match query now runs as
db.Tasks.Where(filter.MatchExpression), with two small follow-up queries
(scoped by parent-id IN-lists) for contextual planning-parent rows and
pulled-in children, followed by an explicit re-sort to restore the global
SortOrder/CreatedAt ordering Regroup() depends on.

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

@@ -0,0 +1,57 @@
+using ClaudeDo.Data.Filtering.Filters;
+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
+/// 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>
+public sealed class MatchExpressionSqlTests : IDisposable
+{
+    private readonly string _dbPath;
+    private readonly DbContextOptions<ClaudeDoDbContext> _options;
+
+    public MatchExpressionSqlTests()
+    {
+        _dbPath = Path.Combine(Path.GetTempPath(), $"claudedo_matchexpr_{Guid.NewGuid():N}.db");
+        _options = new DbContextOptionsBuilder<ClaudeDoDbContext>()
+            .UseSqlite($"Data Source={_dbPath}")
+            .Options;
+
+        using var ctx = new ClaudeDoDbContext(_options);
+        ctx.Database.EnsureCreated();
+    }
+
+    public void Dispose()
+    {
+        foreach (var suffix in new[] { "", "-wal", "-shm" })
+            try { File.Delete(_dbPath + suffix); } catch { }
+    }
+
+    [Fact]
+    public void StatusFilter_MatchExpression_translates_to_a_SQL_WHERE_on_status()
+    {
+        var filter = new StatusFilter("virtual:queued", TaskStatus.Queued);
+
+        using var ctx = new ClaudeDoDbContext(_options);
+        var sql = ctx.Tasks.Where(filter.MatchExpression).ToQueryString();
+
+        Assert.Contains("WHERE", sql, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("status", sql, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public void UserListFilter_MatchExpression_translates_to_a_SQL_WHERE_on_list_id()
+    {
+        var filter = new UserListFilter("abc");
+
+        using var ctx = new ClaudeDoDbContext(_options);
+        var sql = ctx.Tasks.Where(filter.MatchExpression).ToQueryString();
+
+        Assert.Contains("WHERE", sql, StringComparison.OrdinalIgnoreCase);
+        Assert.Contains("list_id", sql, StringComparison.OrdinalIgnoreCase);
+    }
+}