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/core/tools/src/py-types.ts

@@ -41,8 +41,8 @@ const IDENTIFIER = /^[\p{XID_Start}_]\p{XID_Continue}*$/u
  * that normalize together would collapse into one declaration. Those names
  * take the subscript path, which carries their exact bytes.
  *
- * `IDENTIFIER` is equivalent to `str.isidentifier()` on Node 22.23.1 vs
- * CPython 3.9.6 tables: the equivalence holds inside the two versions' shared
+ * `IDENTIFIER` matches `str.isidentifier()` (measured on Node 22.23.1 vs
+ * CPython 3.9.6 tables): the equivalence holds inside the two versions' shared
  * tables, and the skew characters below are exactly where that pair diverges.
  * The predicate as a whole is deliberately stricter than `isidentifier()`,
  * which does not test NFKC stability: `'field'.isidentifier()` is True and