gates: the today-override announces itself; malformed no longer swallowed

Part 6 of the hub-blindness task, separable and done rather than dropped.

Both due_checks_gate.py and instructions_gate.py read FELHOM_GATE_TODAY so
their suites can control "today", and neither said so. A shell that still has
it exported -- exactly what a session doing gate-test work leaves behind --
made both gates evaluate against a fabricated date and pass in SILENCE. That
is this project's own named failure class: an instrument that can quietly
return the wrong answer is not a measurement. The seam is legitimate and
stays; the silence was the defect.

Both now print a loud line naming the variable, its value, and that the real
date is being ignored, before any verdict.

And instructions_gate.py no longer swallows a MALFORMED override: it used to
fall through to the real date without a word while due_checks_gate.py already
exited 2 on the same input -- one variable, two gates, disagreeing about what
a mistake means. Both exit 2 now.

Tests extended in both suites (42 and 73 assertions, green). Red-proof: the
announcement was deleted from due_checks_gate.py and its two assertions were
seen failing, then reverted.

Also adds REPORT-hub-blindness.md (topic-suffixed; the shared REPORT.md is
left alone per the parallel-session rule).

scripts/CHANGELOG.md

@@ -1,3 +1,21 @@
+## due_checks_gate.py v1.0.1 + instructions_gate.py — the today-override announces itself (2026-08-18)
+
+**Both gates read `FELHOM_GATE_TODAY` so their suites can control "today"; neither said so.** A shell
+that still has it exported — exactly what a session doing gate-test work leaves behind — made both
+gates evaluate against a fabricated date and pass, **silently**. That is this project's own named
+failure class: an instrument that can quietly return the wrong answer is not a measurement. The seam
+is legitimate and stays; the silence was the defect.
+
+- Both gates now print a loud line naming the variable, its value, and that the real date is being
+  ignored, before any verdict.
+- **`instructions_gate.py` no longer swallows a MALFORMED override.** It used to fall through to the
+  real date without a word, while `due_checks_gate.py` already exited 2 on the same input — two gates
+  reading one variable and disagreeing about what a mistake means. Both now exit 2.
+
+Tests extended in both suites (valid → announced; malformed → exit 2). One red-proof: the
+announcement was deleted from `due_checks_gate.py` and its two assertions were seen failing, then
+reverted.
+
 ## due_checks_gate.py v1.0.0 — a dated check becomes a thing that bites (2026-08-18, R-341)
 
 **New gate, registered as #10 in `repo_gates.py` (`--fast`).** R-341 booked two dated measurements —