justify, which the site could always render

`rt-justify` has been in the sanitiser's allowlist all along, and styles.css gives it `text-align:
justify` with `hyphens: auto` — hyphenation being what stops justified text opening rivers of white
space between words. Only the toolbar was missing it.

The four are now a list beside the toolbar rather than a ternary chain, and the comment says what it has
to match: ALIGN_CLASSES in the site's rich-text.ts. A fifth offered here would be stripped on save,
silently, leaving somebody pressing a button that appears to do nothing.

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

web/RichText.tsx

@@ -5,6 +5,7 @@ import Link from '@tiptap/extension-link';
 import TextAlign from '@tiptap/extension-text-align';
 import {
   AlignCenter,
+  AlignJustify,
   AlignLeft,
   AlignRight,
   Bold,
@@ -30,7 +31,7 @@ import {
  *
  * ── The toolbar is what the site can actually render ──
  *
- * Bold, italic, strike, a heading, two lists, three alignments, a link. Not because tiptap cannot do
+ * Bold, italic, strike, a heading, two lists, four alignments, a link. Not because tiptap cannot do
  * more, but because anything offered here that the site's stylesheet has no rule for produces copy that
  * looks right while editing and wrong when published — the worst kind of editor, since the person only
  * finds out after saying it is done.
@@ -75,6 +76,19 @@ const Tool = ({
   </button>
 );
 
+/**
+ * The alignments the toolbar offers.
+ *
+ * The same four the site's sanitiser accepts — ALIGN_CLASSES in src/rich-text.ts. A fifth offered here
+ * would be stripped on save, silently, leaving somebody pressing a button that appears to do nothing.
+ */
+const ALIGNMENTS = [
+  { value: 'left' as const, Icon: AlignLeft },
+  { value: 'center' as const, Icon: AlignCenter },
+  { value: 'right' as const, Icon: AlignRight },
+  { value: 'justify' as const, Icon: AlignJustify },
+];
+
 const Toolbar = ({ editor }: { editor: Editor }) => (
   <div className="flex flex-wrap items-center gap-0.5 border-b border-border px-1 py-1">
     <Tool label="Bold" onClick={() => editor.chain().focus().toggleBold().run()} active={editor.isActive('bold')}>
@@ -117,20 +131,21 @@ const Toolbar = ({ editor }: { editor: Editor }) => (
 
     <span className="mx-1 h-4 w-px bg-border" />
 
-    {(['left', 'center', 'right'] as const).map((align) => (
+    {/*
+      Four alignments, justify included.
+
+      The site has always been able to render it: `rt-justify` is in the sanitiser's allowlist and
+      styles.css gives it `text-align: justify` with `hyphens: auto` — hyphenation being what stops
+      justified text opening rivers of white space between words. Only the toolbar was missing.
+    */}
+    {ALIGNMENTS.map(({ value, Icon }) => (
       <Tool
-        key={align}
-        label={`Align ${align}`}
-        onClick={() => editor.chain().focus().setTextAlign(align).run()}
-        active={editor.isActive({ textAlign: align })}
+        key={value}
+        label={`Align ${value}`}
+        onClick={() => editor.chain().focus().setTextAlign(value).run()}
+        active={editor.isActive({ textAlign: value })}
       >
-        {align === 'left' ? (
-          <AlignLeft className="size-3.5" />
-        ) : align === 'center' ? (
-          <AlignCenter className="size-3.5" />
-        ) : (
-          <AlignRight className="size-3.5" />
-        )}
+        <Icon className="size-3.5" />
       </Tool>
     ))}