Add explicit per-plan gauge temperature offset

public/app.css

@@ -4463,3 +4463,7 @@ select.f {
  .calendar-toolbar button { padding-left:8px; padding-right:8px; }
  .calendar-toolbar select { grid-column:1 / -1; width:100%; max-width:none; }
 }
+
+.plan-temperature-offset { display:grid; grid-template-columns:minmax(180px,240px) 1fr; gap:16px; align-items:center; margin:16px 0; padding:16px; border:1px solid var(--line); border-radius:10px; background:#faf8f5; }
+.plan-temperature-offset .field-note { margin:0; line-height:1.5; }
+@media(max-width:700px) { .plan-temperature-offset { grid-template-columns:1fr; gap:10px; } }

public/js/planner-workspace.js

@@ -115,6 +115,20 @@ export function initPlannerWorkspace({
 			"field-note",
 		),
 	);
+	const calibration = n("div", "", "plan-temperature-offset");
+	const offsetLabel = n("label", "", "field");
+	offsetLabel.append(n("span", "Gauge temperature offset (°F)", "field-label"));
+	const offsetInput = n("input", "", "field-input");
+	offsetInput.name = "temperatureOffsetF";
+	offsetInput.type = "number";
+	offsetInput.step = "any";
+	offsetInput.placeholder = "0";
+	offsetInput.setAttribute("aria-describedby", "temperature-offset-help");
+	offsetLabel.append(offsetInput);
+	const offsetHelp = n("p", "Gauge reads 50°F lower? Enter −50. Shifts blank event-temperature references; drop follows the adjusted milestones. Entered temperatures, preheat and recorded roasts stay as entered.", "field-note");
+	offsetHelp.id = "temperature-offset-help";
+	calibration.append(offsetLabel, offsetHelp);
+	curve.append(calibration);
 	const overview = n("section", "", "plan-overview");
 	overview.append(n("span", "YOUR NEXT BATCH", "eyebrow"));
 	const stats = n("div", "", "overview-stats");