fix(module-federation): remove trailing slash from @mui/material/styles shared dependency key

The shared dependency key `@mui/material/styles/` (with trailing slash) caused
module resolution failures because MUI's package.json exports map only defines
`./styles`, not `./styles/`. This resulted in errors like:

  Package subpath './styles/' is not defined by "exports" in
  @mui/material/package.json

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/fix-mui-styles-shared-dep.md

@@ -0,0 +1,5 @@
+---
+'@backstage/module-federation-common': patch
+---
+
+Fixed the `@mui/material/styles` shared dependency key by removing a trailing slash that caused module resolution failures with MUI package exports.

.patches/pr-32996.txt

@@ -0,0 +1 @@
+Fixes the `@mui/material/styles` shared dependency key by removing a trailing slash that caused module resolution failures with MUI package exports.

packages/frontend-dynamic-feature-loader/src/loader.test.tsx

@@ -165,7 +165,7 @@ describe('dynamicFrontendFeaturesLoader', () => {
       shareConfig: { singleton: true, requiredVersion: '*', eager: true },
     },
     {
-      name: '@mui/material/styles/',
+      name: '@mui/material/styles',
       version: '5.16.14',
       lib: async () => ({ default: {} }),
       shareConfig: { singleton: true, requiredVersion: '*', eager: true },

packages/module-federation-common/src/defaults.ts

@@ -55,7 +55,7 @@ const defaultSharedDependencies = {
   // MUI v5
   // not setting import: false for MUI packages as this
   // will break once Backstage moves to BUI
-  '@mui/material/styles/': {
+  '@mui/material/styles': {
     host: {},
     remote: {},
   },