chore(urls): stop claiming path-prefixed base URLs are supported

The previous commit's doc and test said a path-prefixed base keeps its path.
That reads as support for a deployment shape the app does not have: there is no
Next `basePath`, so routes are served at the origin root and such a value could
not address them however the base were normalized. Every documented example is
origin-only.

Says only what is true — trailing slashes are the one spelling absorbed — and
reframes the test as pinning the trim's shape rather than asserting a
path-prefixed deployment works. No behavior change.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: icecrasher321

apps/sim/lib/core/utils/urls.test.ts

@@ -74,11 +74,16 @@ describe('getBaseUrl', () => {
     }
   })
 
-  it('keeps the path of a path-prefixed base URL', () => {
+  /**
+   * Pins the trim's shape — it must not eat more than the trailing slashes.
+   * Not a claim that a path-prefixed deployment works: the app declares no Next
+   * `basePath`, so such a value could not address its routes either way.
+   */
+  it('trims only trailing slashes, never interior ones', () => {
     mockGetEnv.mockImplementation((key) =>
-      key === 'NEXT_PUBLIC_APP_URL' ? 'https://example.com/sim/' : undefined
+      key === 'NEXT_PUBLIC_APP_URL' ? 'https://example.com/a/b/' : undefined
     )
-    expect(getBaseUrl()).toBe('https://example.com/sim')
+    expect(getBaseUrl()).toBe('https://example.com/a/b')
   })
 
   it('adds the protocol and strips the trailing slash together', () => {

apps/sim/lib/core/utils/urls.ts

@@ -22,7 +22,11 @@ function hasHttpProtocol(url: string): boolean {
  * route, and breaks the `startsWith(`${base}/`)` prefix checks that decide
  * whether a redirect target is our own. Normalizing once here is what lets
  * those call sites stay simple instead of each defending against the operator's
- * spelling. A path-prefixed base (`https://host/sim/`) keeps its path.
+ * spelling.
+ *
+ * Trailing slashes are the only spelling this absorbs. The app declares no Next
+ * `basePath`, so its routes are served at the origin root and a path-prefixed
+ * value could not address them however this normalized it.
  */
 function normalizeBaseUrl(url: string): string {
   const protocol = isProd ? 'https://' : 'http://'