Polish Bean Bro setup errors and preserve empty plan names

server/llm.js

@@ -38,7 +38,7 @@ export async function pickModel(preferred = null) {
 
 /** Consistent error for "the server has no usable model" across features. */
 export function noModelError() {
-  const err = new Error("No LLM model is configured on the server.");
+  const err = new Error("Bean Bro is not configured on the server. An admin can choose a provider in Admin → Bean Bro.");
   err.code = "no_model";
   return err;
 }

server/workspace.js

@@ -277,7 +277,7 @@ export async function savePlanRevision(db, userId, id, body) {
 			name =
 				body.name === undefined
 					? existing.name
-					: String(body.name).trim().slice(0, 120);
+					: String(body.name ?? "").trim().slice(0, 120);
 		const planning = (p) => {
 			const { assistant, roastDay, ...rest } = p;
 			return rest;