integration: add route metadata, JSON-LD and harden the public shell

Ship prerendered SEO, crawl files and palette/map a11y so every locale route is indexable, honest and keyboard-usable without inventing claims.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/core/content/signature-copy.ts

@@ -1,10 +1,11 @@
+import { type CommandId } from '../commands/command-ids';
 import { type AppLocale } from '../i18n/locale';
-import { type CommandId } from '../../shared/command-palette/commands';
 
 export interface SignatureCopy {
   readonly palette: {
     readonly triggerLabel: string;
     readonly shortcutHint: string;
+    readonly shortcutHintApple: string;
     readonly dialogTitle: string;
     readonly dialogDescription: string;
     readonly inputLabel: string;
@@ -47,6 +48,7 @@ export const SIGNATURE_COPY: Record<AppLocale, SignatureCopy> = {
     palette: {
       triggerLabel: 'Befehle öffnen',
       shortcutHint: 'Strg+K',
+      shortcutHintApple: '⌘K',
       dialogTitle: 'Befehle',
       dialogDescription:
         'Zur Navigation oder zu einer kurzen Rückmeldung. Es wird kein Code ausgeführt.',
@@ -100,6 +102,7 @@ export const SIGNATURE_COPY: Record<AppLocale, SignatureCopy> = {
     palette: {
       triggerLabel: 'Open commands',
       shortcutHint: 'Ctrl+K',
+      shortcutHintApple: '⌘K',
       dialogTitle: 'Commands',
       dialogDescription: 'Navigate or get a short acknowledgement. No code is executed.',
       inputLabel: 'Command',