fix(worker): record real raw token usage per run, not the uncached remainder

task_runs.tokens_in only ever held the API's uncached "input_tokens" field
(off by a factor of ~400,000 on a resumed session), and tokens_out summed
only the last result event instead of the whole session. TaskRunner now
reads each run's cache-read/cache-write/input/output totals from the
session transcript via a new ITranscriptUsageReader.ReadSessionTotalsAsync,
storing the delta against prior runs on the same session so a --resume
doesn't double-count. New task_runs.cache_read_tokens/cache_write_tokens
columns; the Session tab now shows the raw total (what actually counts
against the 5h/7d usage limit) with a breakdown tooltip.

tests/ClaudeDo.Worker.Tests/Infrastructure/FakeTranscriptUsageReader.cs

@@ -0,0 +1,18 @@
+using ClaudeDo.Worker.Usage;
+using ClaudeDo.Worker.Usage.Interfaces;
+
+namespace ClaudeDo.Worker.Tests.Infrastructure;
+
+public sealed class FakeTranscriptUsageReader : ITranscriptUsageReader
+{
+    private readonly Dictionary<string, SessionUsageTotals> _totalsBySession = new();
+
+    public void SetTotals(string sessionId, SessionUsageTotals totals) => _totalsBySession[sessionId] = totals;
+
+    public Task<IReadOnlyList<UsageAggregateRow>> ReadAsync(
+        DateOnly start, DateOnly end, CancellationToken ct = default) =>
+        Task.FromResult<IReadOnlyList<UsageAggregateRow>>(Array.Empty<UsageAggregateRow>());
+
+    public Task<SessionUsageTotals?> ReadSessionTotalsAsync(string sessionId, CancellationToken ct = default) =>
+        Task.FromResult(_totalsBySession.TryGetValue(sessionId, out var totals) ? totals : null);
+}