fix(pm): a population declaration's reason is whole or the declaration is red

The three population markers in `scripts/pm/dispatch-gates.mjs` capture their
reason with `(\S.*)$` under the `m` flag, so the capture ends at the first
newline. A reason an author wraps across two or three comment lines was
captured as line one only, and no refusal ever asked whether it ended where the
author did: `wholeTreePopulationRefusal` checks that a reason EXISTS and that a
root walk BACKS it. The seat was handed a sentence that simply stops — and the
reason is the one thing a seat reads off that row.

The marker grammar now has one spelling (`populationMarkerPattern`), and
`populationReasonContinuation` reads, off the same text, the comment line that
continues a reason. A continued reason is refused by
`populationReasonCutRefusal`, which names the declaration, the file and the
line; the whole-tree and wide refusals delegate to it before the checks that
read the reason text, and the no-path renderer prints a cut declaration as
REFUSED rather than as the fragment it was cut down to.

Live derivation over the tree: 27 declarations, one of them cut —
`check:objectui-bump` reached the seat as "every path this file writes or
reads". Its comment is made whole on one line here, verbatim, so no refusal
lands red on main.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gqi43smmqjJ5sUrhfoPeKu

Author: claude

scripts/bump-objectui.selftest.sh

@@ -47,13 +47,7 @@
 # the real `objectui-changeset-digest.mjs` (a byte copy, like the script under
 # test) through a throwaway objectui repo with a real changeset commit.
 #
-# dispatch-gates: no-path-population -- every path this file writes or reads
-# lives inside a disposable checkout under mktemp -d (a throwaway objectui and
-# a throwaway FRAMEWORK_ROOT, both destroyed by the EXIT trap below), so no
-# quoted literal in this file names a path this repo tracks. Case 5's fixture
-# changeset filename is assembled from CHANGESET_NAME by interpolation
-# everywhere it is used, deliberately never spelled as one bare quoted token,
-# so it does not read as a declared population here either.
+# dispatch-gates: no-path-population -- every path this file writes or reads lives inside a disposable checkout under mktemp -d (a throwaway objectui and a throwaway FRAMEWORK_ROOT, both destroyed by the EXIT trap below), so no quoted literal in this file names a path this repo tracks. Case 5's fixture changeset filename is assembled from CHANGESET_NAME by interpolation everywhere it is used, deliberately never spelled as one bare quoted token, so it does not read as a declared population here either.
 
 set -euo pipefail