fix(chequebook,ctsclearing): surface global stock allocation in UI; fix decided-state check

Receive Stock form now displays the actual highest-allocated serial across
every series (not just silently prefilling the field), so the operator
can see and trust the auto-suggested range start rather than taking it
on faith.

Fixes a real bug where item.decision (which InwardClearingItem.java always
sets to the literal string "PENDING" at creation, never null) was checked
with a plain truthy test everywhere a "has this been decided yet" branch
was needed. Since "PENDING" is a non-empty string, that check was always
true — silently breaking the Decide/View button label, the collapsed
validation summary, the "Awaiting settlement" text, and the decision
dialog itself (which never showed the actual Pass/Return form, even for
still-pending items). Replaced with a proper isDecided() check everywhere.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/chequebook/stock-management/stock-management.component.scss

@@ -92,6 +92,19 @@
   margin-bottom: 16px;
 }
 
+.global-allocation-note {
+  margin-bottom: 14px;
+  padding: 8px 12px;
+  border-radius: 4px;
+  background: rgb(25 118 210 / 8%);
+  color: rgb(0 0 0 / 70%);
+  font-size: 0.85rem;
+
+  strong {
+    font-variant-numeric: tabular-nums;
+  }
+}
+
 .form-grid {
   display: grid;
   grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));