fix: link dataforest cloud with /en again

The 5.1.0 popup, the sponsor panel in Settings > About and the README had
switched to https://cloud.dataforest.net/?mtm_campaign=trek. The link stays
https://cloud.dataforest.net/en?mtm_campaign=trek everywhere.

README.md

@@ -36,7 +36,7 @@ TREK has grown from a travel planner into a whole ecosystem for trips: plan toge
  
 <a href="https://github.com/liketrek/TREK"><img alt="Stars" src="https://img.shields.io/github/stars/liketrek/trek?style=for-the-badge&label=Stars&color=6B7280" /></a>
 
-<sub>PUBLIC SERVICES PROUDLY SPONSORED BY</sub><br /><a href="https://cloud.dataforest.net/?mtm_campaign=trek"><picture><source media="(prefers-color-scheme: dark)" srcset="docs/sponsors/dataforest-light.svg" /><source media="(prefers-color-scheme: light)" srcset="docs/sponsors/dataforest-dark.svg" /><img src="docs/sponsors/dataforest-dark.svg" alt="dataforest cloud" height="30" /></picture></a>
+<sub>PUBLIC SERVICES PROUDLY SPONSORED BY</sub><br /><a href="https://cloud.dataforest.net/en?mtm_campaign=trek"><picture><source media="(prefers-color-scheme: dark)" srcset="docs/sponsors/dataforest-light.svg" /><source media="(prefers-color-scheme: light)" srcset="docs/sponsors/dataforest-dark.svg" /><img src="docs/sponsors/dataforest-dark.svg" alt="dataforest cloud" height="30" /></picture></a>
 </div>
 
 ---
@@ -224,7 +224,7 @@ Most of what follows is an addon an admin switches on or off. Lists, Costs, Docu
 
 <br />
 
-<a href="https://cloud.dataforest.net/?mtm_campaign=trek">
+<a href="https://cloud.dataforest.net/en?mtm_campaign=trek">
   <picture>
     <source media="(prefers-color-scheme: dark)" srcset="docs/sponsors/dataforest-light.svg" />
     <source media="(prefers-color-scheme: light)" srcset="docs/sponsors/dataforest-dark.svg" />
@@ -243,7 +243,7 @@ Thank you, dataforest, for backing open source this generously. 💚
 
 <br />
 
-<a href="https://cloud.dataforest.net/?mtm_campaign=trek"><img alt="Visit dataforest cloud" src="https://img.shields.io/badge/Visit-dataforest_cloud-02C382?style=for-the-badge" /></a>
+<a href="https://cloud.dataforest.net/en?mtm_campaign=trek"><img alt="Visit dataforest cloud" src="https://img.shields.io/badge/Visit-dataforest_cloud-02C382?style=for-the-badge" /></a>
 
 Looking for a server for your own TREK? dataforest cloud is where TREK's own services live.
 
@@ -277,7 +277,7 @@ Open `http://localhost:3000`, or `http://<server-ip>:3000` from another machine.
 `COOKIE_SECURE=false` is only for trying TREK over plain HTTP: without it the browser drops the session cookie and the login does not stick. Once TREK sits behind HTTPS (see [Reverse Proxy](#reverse-proxy)), remove it.
 
 > [!TIP]
-> **No server yet?** TREK's own public services run on [**dataforest cloud**](https://cloud.dataforest.net/?mtm_campaign=trek), our infrastructure sponsor. A small seed is plenty for a TREK instance and is ready within a minute.
+> **No server yet?** TREK's own public services run on [**dataforest cloud**](https://cloud.dataforest.net/en?mtm_campaign=trek), our infrastructure sponsor. A small seed is plenty for a TREK instance and is ready within a minute.
 
 <div align="center">
 

client/src/components/Settings/AboutTab.test.tsx

@@ -134,7 +134,7 @@ describe('AboutTab', () => {
 
   it('FE-COMP-ABOUT-018: the sponsor panel links dataforest cloud wherever it is named, with both logos bundled', () => {
     render(<AboutTab appVersion="1.0.0" />);
-    const links = document.querySelectorAll('a[href="https://cloud.dataforest.net/?mtm_campaign=trek"]');
+    const links = document.querySelectorAll('a[href="https://cloud.dataforest.net/en?mtm_campaign=trek"]');
     // The logo tile, the call to action, and the brand name in the title and in the body.
     expect(links).toHaveLength(4);
     for (const link of links) {

client/src/components/Settings/AboutTab.tsx

@@ -93,7 +93,7 @@ function LinkTile({
   );
 }
 
-const DATAFOREST_HREF = 'https://cloud.dataforest.net/?mtm_campaign=trek';
+const DATAFOREST_HREF = 'https://cloud.dataforest.net/en?mtm_campaign=trek';
 const DATAFOREST_NAME = 'dataforest cloud';
 const DATAFOREST = '#02C382'; // theme-lint-disable: brand colour (dataforest cloud)
 

client/src/components/SystemNotices/ReleaseNoticeModal.test.tsx

@@ -239,7 +239,7 @@ describe('ReleaseNoticeModal', () => {
     const links = screen.getAllByRole('link', { name: 'dataforest cloud' });
     expect(links).toHaveLength(2);
     for (const link of links) {
-      expect(link).toHaveAttribute('href', 'https://cloud.dataforest.net/?mtm_campaign=trek');
+      expect(link).toHaveAttribute('href', 'https://cloud.dataforest.net/en?mtm_campaign=trek');
       expect(link).toHaveAttribute('target', '_blank');
       expect(link).toHaveAttribute('rel', 'noopener noreferrer');
     }

client/src/components/SystemNotices/ReleaseNoticeModal.tsx

@@ -38,7 +38,7 @@ function SteamingCoffee() {
 }
 
 const SPONSOR = 'dataforest cloud';
-const SPONSOR_HREF = 'https://cloud.dataforest.net/?mtm_campaign=trek';
+const SPONSOR_HREF = 'https://cloud.dataforest.net/en?mtm_campaign=trek';
 
 /** The sponsor's name is a brand and reads the same in every language, so wherever a line names it, it links. */
 function withSponsorLink(text: string): React.ReactNode {