fix(workspace): tighten link preview card, slash menu matching/scrolling, and Enter on last empty bullet

frontend/src/lib/__tests__/linkPreview.test.ts

@@ -1,14 +1,16 @@
 import { describe, expect, it } from 'vitest';
-import { firstBareUrl, hidePreviewContent } from '../linkPreview';
+import { linkCardUrl, hidePreviewContent } from '../linkPreview';
 
 describe('link preview helpers', () => {
-  it('finds the first plain https address', () => {
-    expect(firstBareUrl('https://example.com/a?b=1')).toBe('https://example.com/a?b=1');
-    expect(firstBareUrl('Rezept: https://koch.de/spaetzle, lecker!')).toBe('https://koch.de/spaetzle');
-    expect(firstBareUrl('siehe (https://x.de/p).')).toBeNull(); // inside brackets: not a plain address
-    expect(firstBareUrl('[Kochseite](https://koch.de)')).toBeNull();
-    expect(firstBareUrl('http://unsicher.de')).toBeNull();
-    expect(firstBareUrl('nur Text')).toBeNull();
+  it('returns the URL only when the entire trimmed content is a single https address', () => {
+    expect(linkCardUrl('https://example.com/a?b=1')).toBe('https://example.com/a?b=1');
+    expect(linkCardUrl('  https://example.com/page/  ')).toBe('https://example.com/page/');
+    expect(linkCardUrl('Rezept: https://koch.de/spaetzle, lecker!')).toBeNull();
+    expect(linkCardUrl('https://a.de https://b.de')).toBeNull();
+    expect(linkCardUrl('siehe (https://x.de/p).')).toBeNull();
+    expect(linkCardUrl('[Kochseite](https://koch.de)')).toBeNull();
+    expect(linkCardUrl('http://unsicher.de')).toBeNull();
+    expect(linkCardUrl('nur Text')).toBeNull();
   });
 
   it('hides a preview by turning the address into a named link', () => {
@@ -16,6 +18,6 @@ describe('link preview helpers', () => {
       'Lesen: [Käsespätzle Rezept](https://koch.de/x)'
     );
     expect(hidePreviewContent('https://koch.de/x', 'https://koch.de/x', '')).toBe('[koch.de](https://koch.de/x)');
-    expect(firstBareUrl(hidePreviewContent('https://koch.de/x', 'https://koch.de/x', 'T'))).toBeNull();
+    expect(linkCardUrl(hidePreviewContent('https://koch.de/x', 'https://koch.de/x', 'T'))).toBeNull();
   });
 });

frontend/src/lib/linkPreview.ts

@@ -16,12 +16,12 @@ export interface LinkPreview {
   ok: boolean;
 }
 
-// First plain https address in a text (not inside [text](url), not right after "(" or "<")
-const BARE_URL_RE = /(^|[\s])(https:\/\/[^\s<>()\]]+[^\s<>()\].,;:!?'"])/;
+// Entire bullet content (trimmed) is a single plain https address
+const CARD_URL_RE = /^https:\/\/[^\s<>()\]]+[^\s<>()\].,;:!?'"]$/;
 
-export function firstBareUrl(content: string): string | null {
-  const m = BARE_URL_RE.exec(content || '');
-  return m ? m[2] : null;
+export function linkCardUrl(content: string): string | null {
+  const trimmed = (content || '').trim();
+  return CARD_URL_RE.test(trimmed) ? trimmed : null;
 }
 
 /** Replaces the address by a named link, which shows no preview. */