fix(dashboard): resolve button calls /resolve endpoint, not PATCH

PATCH /decisions/{id}/ is a blind field-setter with no decided_at logic.
POST /decisions/{id}/resolve is the correct endpoint — it auto-sets
decided_at and emits a decision_resolved progress event.

Fixes: resolved decisions showing last in the sorted list because
decided_at was never populated.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dashboard/src/decisions.md

@@ -347,10 +347,10 @@ if (filtered.length === 0) {
         placeholder:  "Why is this resolved, and what was decided?",
         confirmLabel: "Resolve",
         onConfirm: async (rationale) => {
-          const res = await fetch(`${API}/decisions/${d.id}/`, {
-            method: "PATCH",
+          const res = await fetch(`${API}/decisions/${d.id}/resolve`, {
+            method: "POST",
             headers: {"Content-Type": "application/json"},
-            body: JSON.stringify({status: "resolved", rationale, decided_by: "human"}),
+            body: JSON.stringify({rationale, decided_by: "human"}),
           });
           if (!res.ok) throw new Error(`API error ${res.status}`);
         },