fix: remove $[center] MFM function

docs/changelog.md

@@ -8,6 +8,8 @@ Critical security updates are indicated by the :warning: icon.
 ## Unreleased
 
 - Improve timeline UX
+- Remove `$[center]` MFM function
+	- This function was suddenly added last year (https://firefish.dev/firefish/firefish/-/commit/1a971efa689323d54eebb4d3646e102fb4d1d95a), but according to the [MFM spec](https://github.com/misskey-dev/mfm.js/blob/develop/docs/syntax.md#fn), `$[something]` must be an inline element (while `center` is a block element), so such a syntax is not expected by MFM renderers. Please use `<center></center>` instead.
 - Fix bugs
 
 ## [v20240504](https://firefish.dev/firefish/firefish/-/merge_requests/10790/commits)

packages/client/src/components/mfm.ts

@@ -349,17 +349,6 @@ export default defineComponent({
 										),
 									];
 								}
-								case "center": {
-									return [
-										h(
-											"div",
-											{
-												style: "text-align: center;",
-											},
-											genEl(token.children),
-										),
-									];
-								}
 							}
 							if (style == null) {
 								return [

packages/client/src/pages/mfm-cheat-sheet.vue

@@ -464,9 +464,7 @@ const preview_bold = ref(`**${i18n.ts._mfm.dummy}**`);
 const preview_small = ref(
 	`<small>${i18n.ts._mfm.dummy}</small> $[small ${i18n.ts._mfm.dummy}]`,
 );
-const preview_center = ref(
-	`<center>${i18n.ts._mfm.dummy}</center>\n$[center ${i18n.ts._mfm.dummy}]`,
-);
+const preview_center = ref(`<center>${i18n.ts._mfm.dummy}</center>`);
 const preview_inlineCode = ref('`<: "Hello, world!"`');
 const preview_blockCode = ref(
 	'```\n~ (#i, 100) {\n\t<: ? ((i % 15) = 0) "FizzBuzz"\n\t\t.? ((i % 3) = 0) "Fizz"\n\t\t.? ((i % 5) = 0) "Buzz"\n\t\t. i\n}\n```',

packages/client/src/scripts/mfm-tags.ts

@@ -22,5 +22,4 @@ export const MFM_TAGS = [
 	"rotate",
 	"fade",
 	"small",
-	"center",
 ];