docs: fix review findings — residual ordinals, hypothetical IPC row, citation-rule amendments

Purge the residual task/phase ordinals review caught ((T2), (queue cut 1)
×3, T6, P-I, 'this cut' ×6 including battery-expansion finds in two
untouched notes and a workflow JSDoc); drop the 'externally logged as
Decision 21' parenthetical and rename the remaining bare decision-21
mentions; mark the gui-layering IPC bridge row as a hypothetical example;
restore the GATE_NOTICE doc-typecheck clause and the py-types 'measured'
provenance; say subprocess-backed in filesystem.md; add the picker note
path. Amend the citations note: merged-PR evidence anchors in Agent Notes
are sanctioned, and the candidate gate patterns gain the four shapes the
sweep missed. All nine touched pairs re-recorded.

packages/workflow/workflow/src/index.ts

@@ -126,7 +126,7 @@ export type WorkflowErrorCode =
  * discipline: `parallel()`/`pipeline()` re-throw a fatal error (a typo'd
  * option or a tripped cap must kill the script loudly), and reserve the
  * per-item `null` for child-run failures and ordinary in-stage script errors.
- * Every {@link WorkflowErrorCode} is fatal in this cut; the flag exists so the
+ * Every {@link WorkflowErrorCode} is fatal; the flag exists so the
  * distinction is explicit at every catch site rather than implied.
  */
 export class WorkflowError extends HarnessError {