fix: Expand spell notes textarea full-width; add inter-spell padding

Split each spell into two table rows: the inputs row (name, MP, targets,
duration, delete) and a full-width notes row (colspan=5). Adds 10px
padding above/below each spell for visual separation between entries.

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

src/fabula-ultima-sheet.css

@@ -765,6 +765,23 @@ input[type="number"] {
   min-height: 55px;
 }
 
+.spell-inputs-row td {
+  border-bottom: none;
+  padding-top: 10px;
+}
+
+.spell-notes-row td {
+  padding-top: 0;
+  padding-bottom: 10px;
+}
+
+.spell-notes-row textarea {
+  display: block;
+  width: 100%;
+  min-height: 0;
+  box-sizing: border-box;
+}
+
 .spell-name-col {
   width: 35%;
 }