fix(editor): blur ContentEditor on Escape

ESC did nothing inside the issue description editor because browsers
don't blur contenteditable elements by default, leaving users stuck in
the editor with no keyboard escape hatch.

Add a blur-shortcut extension mirroring TitleEditor's behavior and wire
it into ContentEditor's edit-mode extension set.

packages/views/editor/extensions/blur-shortcut.ts

@@ -0,0 +1,20 @@
+import { Extension } from "@tiptap/core";
+
+/**
+ * Escape → blur the editor. Without this, pressing ESC inside the
+ * contenteditable does nothing (browsers don't blur contenteditables by
+ * default), leaving users stuck in the editor with no keyboard escape hatch.
+ */
+export function createBlurShortcutExtension() {
+  return Extension.create({
+    name: "blurShortcut",
+    addKeyboardShortcuts() {
+      return {
+        Escape: ({ editor }) => {
+          editor.commands.blur();
+          return true;
+        },
+      };
+    },
+  });
+}

packages/views/editor/extensions/index.ts

@@ -40,6 +40,7 @@ import { createMentionSuggestion } from "./mention-suggestion";
 import { CodeBlockView } from "./code-block-view";
 import { createMarkdownPasteExtension } from "./markdown-paste";
 import { createSubmitExtension } from "./submit-shortcut";
+import { createBlurShortcutExtension } from "./blur-shortcut";
 import { createFileUploadExtension } from "./file-upload";
 import { FileCardExtension } from "./file-card";
 import { ImageView } from "./image-view";
@@ -137,6 +138,7 @@ export function createEditorExtensions(
         },
         { submitOnEnter: options.submitOnEnter ?? false },
       ),
+      createBlurShortcutExtension(),
       createFileUploadExtension(options.onUploadFileRef!),
     );
   }