Let temperature formatting ship without dashboard bulk

Temperature formatting was embedded in the large dashboard utility module, so small scan-terminal views had to import the heavy utility surface for simple labels. This moves the pure temperature helpers into a lightweight module while keeping dashboard-utils re-exports for compatibility.

Constraint: Preserve existing temperature text output and all dashboard-utils import compatibility.

Rejected: Split chart, pace, and model helpers in the same pass | those helpers have wider coupling and should move one boundary at a time.

Confidence: high

Scope-risk: narrow

Reversibility: clean

Tested: TypeScript diagnostics for temperature-utils, dashboard-utils, and OpportunityTable

Tested: npm run build

Not-tested: Bundle analyzer size comparison.

frontend/lib/temperature-utils.ts

@@ -0,0 +1,35 @@
+export function normalizeTemperatureSymbol(value?: string | null) {
+  return String(value || "").toUpperCase().includes("F") ? "°F" : "°C";
+}
+
+export function formatTemperatureValue(
+  value: number | null | undefined,
+  symbol?: string | null,
+  options?: { signed?: boolean; digits?: number },
+) {
+  const numeric = Number(value);
+  if (!Number.isFinite(numeric)) return "--";
+  const digits = options?.digits ?? 0;
+  const sign = options?.signed && numeric >= 0 ? "+" : "";
+  return `${sign}${numeric.toFixed(digits)}${normalizeTemperatureSymbol(symbol)}`;
+}
+
+export function normalizeTemperatureLabel(
+  label?: string | null,
+  fallbackSymbol?: string | null,
+) {
+  const raw = String(label || "").trim();
+  if (!raw) return "";
+  const normalizedSymbol = normalizeTemperatureSymbol(fallbackSymbol);
+  let next = raw.replace(/℃/gi, "°C");
+  next = next.replace(/°?([CF])\b/gi, (_, unit: string) => `°${unit.toUpperCase()}`);
+  if (!/[°][CF]/.test(next) && /\d/.test(next)) {
+    next = `${next}${normalizedSymbol}`;
+  }
+  if (normalizedSymbol === "°F") {
+    next = next.replace(/°C/g, "°F");
+  } else {
+    next = next.replace(/°F/g, "°C");
+  }
+  return next;
+}