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.

src/ClaudeDo.Worker/Usage/UsageModels.cs

@@ -32,3 +32,11 @@ public sealed record UsageAggregateRow(
     long CacheReadTokens,
     long CacheCreationTokens,
     int Messages);
+
+/// <summary>Cumulative raw token usage for one Claude Code session (all its transcript
+/// lines to date), synthetic messages excluded. Not a per-run delta.</summary>
+public sealed record SessionUsageTotals(
+    long InputTokens,
+    long OutputTokens,
+    long CacheReadTokens,
+    long CacheCreationTokens);