[TASK] Re-add extension-key to styleguide's composer.json

The extension key setting was accidentally dropped in one
of the monorepo merge preparation changes:
#475

Also reformat to use tabs as in other composer.json files.

Resolves: #102309
Releases: main
Change-Id: I97f6864551b524b27e770a5a046a77744fedf5e3
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81674
Reviewed-by: Andreas Kienast <a.fernandez@scripting-base.de>
Tested-by: Benjamin Franzke <ben@bnf.dev>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Kienast <a.fernandez@scripting-base.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benjamin Franzke <ben@bnf.dev>
Reviewed-by: Jasmina Ließmann <minapokhalo+typo3@gmail.com>

composer.json

@@ -1,36 +1,39 @@
 {
-    "name": "typo3/cms-styleguide",
-    "type": "typo3-cms-framework",
-    "description": "TYPO3 extension to showcase TYPO3 Backend capabilities",
-    "authors": [{
-        "name": "TYPO3 Core Team",
-        "email": "typo3cms@typo3.org",
-        "role": "Developer"
-    }],
-    "homepage": "https://typo3.org",
-    "license": "GPL-2.0-or-later",
-    "keywords": [
-        "typo3",
-        "typo3 backend",
-        "style guide"
-    ],
-    "support": {
-        "chat": "https://typo3.org/help",
-        "docs": "https://docs.typo3.org",
-        "issues": "https://forge.typo3.org",
-        "source": "https://github.com/typo3/typo3"
-    },
-    "autoload": {
-        "psr-4": {
-            "TYPO3\\CMS\\Styleguide\\": "Classes/"
-        }
-    },
-    "config": {
-        "sort-packages": true
-    },
-    "extra": {
-        "branch-alias": {
-            "dev-main": "13.0.x-dev"
-        }
-    }
+	"name": "typo3/cms-styleguide",
+	"type": "typo3-cms-framework",
+	"description": "TYPO3 extension to showcase TYPO3 Backend capabilities",
+	"authors": [{
+		"name": "TYPO3 Core Team",
+		"email": "typo3cms@typo3.org",
+		"role": "Developer"
+	}],
+	"homepage": "https://typo3.org",
+	"license": "GPL-2.0-or-later",
+	"keywords": [
+		"typo3",
+		"typo3 backend",
+		"style guide"
+	],
+	"support": {
+		"chat": "https://typo3.org/help",
+		"docs": "https://docs.typo3.org",
+		"issues": "https://forge.typo3.org",
+		"source": "https://github.com/typo3/typo3"
+	},
+	"autoload": {
+		"psr-4": {
+			"TYPO3\\CMS\\Styleguide\\": "Classes/"
+		}
+	},
+	"config": {
+		"sort-packages": true
+	},
+	"extra": {
+		"typo3/cms": {
+			"extension-key": "styleguide"
+		},
+		"branch-alias": {
+			"dev-main": "13.0.x-dev"
+		}
+	}
 }