Add green-bean inventory and cupping features

Ports inventory management and SCA-style cupping scoring from
hope_roaster: lot tracking with audit-logged consumption, cupping
sessions with server-authoritative scoring and a live radar chart,
and links from the planner (draw-from-lot, open-cupping-session).

Also fixes the Blend/Single-origin toggle layout, replaces tooltips
with an in-context "why" teaching layer, and stages the planner UI
into pre-roast vs. post-roast phases.

public/js/toast.js

@@ -0,0 +1,18 @@
+function stack() {
+	let el = document.querySelector(".toast-stack");
+	if (!el) {
+		el = document.createElement("div");
+		el.className = "toast-stack";
+		el.setAttribute("aria-live", "polite");
+		document.body.append(el);
+	}
+	return el;
+}
+
+export function showToast(text, type = "") {
+	const toast = document.createElement("div");
+	toast.className = `toast ${type}`.trim();
+	toast.textContent = text;
+	stack().append(toast);
+	setTimeout(() => toast.remove(), 4500);
+}