docs(integrity): correct the --dry-run line in the subcommand comment (#3739)

The comment listed `gbrain integrity --dry-run` as a subcommand, but
runIntegrity dispatches on `check`/`auto` and parses --dry-run inside
the auto path, so that form exits 1 with "Unknown subcommand". The
runtime help already shows --dry-run indented under `auto [options]`;
only the source comment disagreed.

Addresses #3738.

src/commands/integrity.ts

@@ -12,7 +12,7 @@
  * Subcommands:
  *   gbrain integrity check              Read-only report to stdout
  *   gbrain integrity auto               Three-bucket repair with confidence
- *   gbrain integrity --dry-run          Same as auto, no writes
+ *   gbrain integrity auto --dry-run     Same as auto, no writes
  *
  * Three-bucket confidence (contract with x_handle_to_tweet resolver):
  *   >= 0.8 → auto-repair through BrainWriter transaction