Fix inventory dialog: hidden form-row not hiding due to display:flex override

Also clarify notes label as per-location, not per-component.

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

public/style.css

@@ -789,6 +789,10 @@ nav {
 	margin-bottom: 0.9rem;
 }
 
+.form-row[hidden] {
+	display: none;
+}
+
 .form-row label {
 	font-size: 0.8rem;
 	text-transform: uppercase;

public/templates.html

@@ -457,7 +457,7 @@
 				<input type="text" id="i-qty" autocomplete="off" placeholder="e.g. 10, ~50, see BOM">
 			</div>
 			<div class="form-row">
-				<label for="i-notes">Notes</label>
+				<label for="i-notes">Notes <span class="label-hint">(for this location entry)</span></label>
 				<input type="text" id="i-notes" autocomplete="off">
 			</div>
 			<div class="dialog-actions">