Add @backstage/cli-defaults package

Introduces a new `@backstage/cli-defaults` package that re-exports all
standard CLI modules as a single array, simplifying dependency management
for consumers. The CLI's `CliInitializer` is updated to support array
exports alongside single module exports. The create-app template,
changesets, and CLI fallback are updated to use `@backstage/cli-defaults`
instead of listing 11 individual modules.

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

.changeset/cli-defaults-introduce.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli-defaults': minor
+---
+
+Introduced `@backstage/cli-defaults`, a convenience package that bundles all standard Backstage CLI modules. Install this single package as a `devDependency` to get the full default set of CLI commands without listing each module individually.

.changeset/cli-discover-modules.md

@@ -4,7 +4,23 @@
 
 The CLI now automatically discovers CLI modules from the project root's `dependencies` and `devDependencies`. Any installed package with the `cli-module` Backstage role will be loaded automatically without needing to be hardcoded in the CLI itself.
 
-If no CLI modules are found in the project dependencies, the CLI falls back to the built-in set of modules and prints a deprecation warning. This fallback will be removed in a future release. To prepare for this, add the following CLI modules as `devDependencies` in your root `package.json`:
+If no CLI modules are found in the project dependencies, the CLI falls back to the built-in set of modules and prints a deprecation warning. This fallback will be removed in a future release. To prepare for this, add `@backstage/cli-defaults` as a `devDependency` in your root `package.json`:
+
+```json
+{
+  "devDependencies": {
+    "@backstage/cli-defaults": "backstage:^"
+  }
+}
+```
+
+If you are not using the Backstage Yarn plugin, run the following instead:
+
+```sh
+yarn workspace root add --dev @backstage/cli-defaults
+```
+
+For fine-grained control you can instead install individual CLI modules:
 
 ```json
 {
@@ -23,9 +39,3 @@ If no CLI modules are found in the project dependencies, the CLI falls back to t
   }
 }
 ```
-
-If you are not using the Backstage Yarn plugin, run the following instead:
-
-```sh
-yarn workspace root add --dev @backstage/cli-module-auth @backstage/cli-module-build @backstage/cli-module-config @backstage/cli-module-create-github-app @backstage/cli-module-info @backstage/cli-module-lint @backstage/cli-module-maintenance @backstage/cli-module-migrate @backstage/cli-module-new @backstage/cli-module-test-jest @backstage/cli-module-translations
-```

.changeset/create-app-cli-modules.md

@@ -2,4 +2,4 @@
 '@backstage/create-app': patch
 ---
 
-The create-app templates now include all standard `@backstage/cli-module-*` packages as `devDependencies`, enabling the CLI's automatic module discovery for newly created projects.
+The create-app templates now include `@backstage/cli-defaults` as a `devDependency`, enabling the CLI's automatic module discovery for newly created projects.