refac: inline codespan rich text input

Co-Authored-By: Abdul Moiz <86627657+abdulmoizjawed@users.noreply.github.com>

src/lib/components/common/RichTextInput.svelte

@@ -114,7 +114,7 @@
 	import { Fragment, DOMParser } from 'prosemirror-model';
 	import { EditorState, Plugin, PluginKey, TextSelection, Selection } from 'prosemirror-state';
 	import { Decoration, DecorationSet } from 'prosemirror-view';
-	import { Editor, Extension, mergeAttributes } from '@tiptap/core';
+	import { Editor, Extension, markInputRule, mergeAttributes } from '@tiptap/core';
 
 	import { AIAutocompletion } from './RichTextInput/AutoCompletion.js';
 
@@ -135,8 +135,26 @@
 	import FileHandler from '@tiptap/extension-file-handler';
 	import Typography from '@tiptap/extension-typography';
 	import Highlight from '@tiptap/extension-highlight';
+	import Code from '@tiptap/extension-code';
 	import CodeBlockLowlight from '@tiptap/extension-code-block-lowlight';
 
+	// WORKAROUND: TipTap's default Code mark input rule regex captures the
+	// character before the opening backtick, causing it to be deleted.
+	// This uses a lookbehind assertion instead so the preceding character is
+	// matched for position but not captured/deleted.
+	// Upstream fix: https://github.com/ueberdosis/tiptap/pull/7124
+	const backtickInputRegex = /(?<=\s|^)`([^`]+)`(?!`)$/;
+	const FixedCode = Code.extend({
+		addInputRules() {
+			return [
+				markInputRule({
+					find: backtickInputRegex,
+					type: this.type
+				})
+			];
+		}
+	});
+
 	import Mention from '@tiptap/extension-mention';
 	import FormattingButtons from './RichTextInput/FormattingButtons.svelte';
 
@@ -692,12 +710,14 @@
 			extensions: [
 				StarterKit.configure({
 					link: link,
+					code: false, // Disabled in favor of FixedCode (see workaround above)
 					// When rich text is off, disable Strike from StarterKit so we can
 					// re-add it below without its Mod-Shift-s shortcut (which conflicts
 					// with the Toggle Sidebar shortcut). When rich text is on, the user
 					// can undo strikethrough via the toolbar, so the shortcut is fine.
 					...(richText ? {} : { strike: false })
 				}),
+				FixedCode,
 				...(dragHandle ? [ListItemDragHandle] : []),
 				Placeholder.configure({ placeholder: () => _placeholder, showOnlyWhenEditable: false }),
 				SelectionDecoration,