Add BMIS number support for business customer rates

Introduces a new `bmisNumber` option to journey requests, allowing bahn.business customers to access corporate rates by providing their 7-digit BMIS number. Adds documentation and a `createBusinessClient` helper for convenience. The request payload now includes a `firmenZugehoerigkeit` object when a BMIS number is set.

docs/journeys.md

@@ -81,6 +81,7 @@ With `opt`, you can override the default options, which look like this:
 	firstClass: false, // first or second class for tickets
 	loyaltyCard: null, // BahnCards etc., see below
 	language: 'en', // language to get results in
+	bmisNumber: null, // 7-digit BMIS number for business customer rates
 }
 ```
 
@@ -316,6 +317,27 @@ hafas.journeys(from, to, {
 })
 ```
 
+## Using the `bmisNumber` option
+
+bahn.business customers with a BMIS number can get their corporate rates and corporate tariffs by providing their 7-digit BMIS number:
+
+```js
+// Option 1: Using the bmisNumber parameter directly
+await client.journeys(from, to, {
+	bmisNumber: '1234567' // Your 7-digit BMIS number
+})
+
+// Option 2: Using the createBusinessClient helper function
+import {createBusinessClient} from 'db-vendo-client'
+import {profile as dbProfile} from 'db-vendo-client/p/db/index.js'
+
+const businessClient = createBusinessClient(dbProfile, userAgent, '1234567')
+// Now all journey searches will automatically include the BMIS number
+await businessClient.journeys(from, to)
+```
+
+When a BMIS number is provided, the request will include a `firmenZugehoerigkeit` object with the BMIS number and identification type, allowing business customers to access their special rates and conditions.
+
 ## The `routingMode` option
 
 The `routingMode` option is not supported by db-vendo-client. The behavior will be the same as the [`HYBRID` mode of hafas-client](https://github.com/public-transport/hafas-client/blob/main/p/db/readme.md#using-the-routingmode-option), i.e. cancelled trains/infeasible journeys will also be contained for informational purpose.

index.js

@@ -183,6 +183,7 @@ const createClient = (profile, userAgent, opt = {}) => {
 			bestprice: false, // search for lowest prices across the entire day
 			deutschlandTicketDiscount: false,
 			deutschlandTicketConnectionsOnly: false,
+			bmisNumber: null, // 7-digit BMIS number for business customer rates
 		}, opt);
 
 		if (opt.when !== undefined) {
@@ -243,6 +244,7 @@ const createClient = (profile, userAgent, opt = {}) => {
 			scheduledDays: false, // parse & expose dates the journey is valid on?
 			deutschlandTicketDiscount: false,
 			deutschlandTicketConnectionsOnly: false,
+			bmisNumber: null, // 7-digit BMIS number for business customer rates
 		}, opt);
 
 		const req = profile.formatRefreshJourneyReq({profile, opt}, refreshToken);
@@ -395,7 +397,33 @@ const createClient = (profile, userAgent, opt = {}) => {
 	return client;
 };
 
+const createBusinessClient = (profile, userAgent, bmisNumber, opt = {}) => {
+	if (!bmisNumber || typeof bmisNumber !== 'string') {
+		throw new TypeError('bmisNumber must be a non-empty string');
+	}
+
+	// Create a client with BMIS number included in all journey requests
+	const client = createClient(profile, userAgent, opt);
+
+	// Wrap journeys method to always include BMIS number
+	const originalJourneys = client.journeys;
+	client.journeys = async (from, to, opt = {}) => {
+		return originalJourneys(from, to, {...opt, bmisNumber});
+	};
+
+	// Wrap refreshJourney method to always include BMIS number
+	if (client.refreshJourney) {
+		const originalRefreshJourney = client.refreshJourney;
+		client.refreshJourney = async (refreshToken, opt = {}) => {
+			return originalRefreshJourney(refreshToken, {...opt, bmisNumber});
+		};
+	}
+
+	return client;
+};
+
 export {
 	createClient,
+	createBusinessClient,
 	loadEnrichedStationData,
 };

p/dbnav/journeys-req.js

@@ -4,7 +4,7 @@ const formatBaseJourneysReq = (ctx) => {
 	// TODO opt.accessibility
 	// TODO routingMode
 	const travellers = ctx.profile.formatTravellers(ctx);
-	return {
+	const baseReq = {
 		autonomeReservierung: false,
 		einstiegsTypList: [
 			'STANDARD',
@@ -27,6 +27,16 @@ const formatBaseJourneysReq = (ctx) => {
 		},
 		reservierungsKontingenteVorhanden: false,
 	};
+
+	// Add business customer affiliation if BMIS number is provided
+	if (ctx.opt.bmisNumber) {
+		baseReq.firmenZugehoerigkeit = {
+			bmisNr: ctx.opt.bmisNumber,
+			identifikationsart: 'BMIS',
+		};
+	}
+
+	return baseReq;
 };
 
 const formatJourneysReq = (ctx, from, to, when, outFrwd, journeysRef) => {