feat(gate): judge a read-seam catch that ANSWERS BY ASSIGNMENT

The read-seam invention rule judges the expression a `catch` RETURNS, so
`catch { return []; }` is red and `catch { ids = []; }` is green — one
invention delivered a statement apart, and only the first is seen. #9261
is where that cost something: `probeInstallOrganizations` answered a
failed `sys_organization` read with an assigned-and-memoised empty list,
system inserts landed unstamped, the mandated multi-org refusal was
skipped, and the gate was green throughout. It was found by the #8901
census re-run, not by this gate.

Third invention criterion, on the same three preconditions (a read in the
`try`, no log at all, no type discrimination): an `inventedEmptyValue`
written into a variable the function declared BEFORE the `try`. It reuses
the value table unchanged — the criterion is about how the invention is
DELIVERED, never about which values count as invented.

⛔ This is NOT #8845's declined fall-through criterion, and the difference
is why it is affordable. #8845 judges a catch that writes NOTHING, which
needs the checker to guess which variable is the answer (15 sites, 7
already correct, and the obvious exemption clears `publishPackageDrafts`'
fabricated push). Here the catch NAMES the variable. `push`/`++`/`+=`
accumulation stays unjudged and #8845's census is unchanged.

Measured before it was added (收窄先行, the #6451 discipline) at 945ffbe
over the three scan roots, 66 read seams: 3 catches carry any plain
assignment, 1 assigns an invented empty value to a pre-`try` name, and the
first-run RED set is 0 — that one site is #9261's own seam, passing
because PR #9817 gave it `isMissingTableError` discrimination. Zero
baseline entries, no new vocabulary, no new declared name.

A criterion whose discoveries are invisible on a green run cannot be told
from a selector that stopped selecting — this card's own subject — so the
green verdict now counts them: 7 type-discriminated seams becomes 8, plus
a named answer-by-assignment count.

Part of #9165

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015ahemw8RcTgqtxrj15PEZx

Author: claude