feat(browser): rework element annotation and picker toolbar

Element annotation is now free-text: dropped the Fix/Change/Question/
Approve intent pills and the intent field, so the user just says what
they want. The card uses the shared Button and is titled "Annotate
element".

Toolbar: the element picker and DevTools are no longer dev-gated and
work in prod; DevTools uses a wrench icon, and the old clipboard "grab"
is now a Camera "Screenshot element" tool. Each toolbar button
highlights only its own mode, and the copy toast reflects whether a
screenshot image was actually captured.

packages/app/src/composer/attachments/workspace-cleanup.ts

@@ -11,7 +11,6 @@ export function getAttachmentKey(attachment: WorkspaceComposerAttachment): strin
       tag: attachment.attachment.tag,
       text: attachment.attachment.text,
       html: attachment.attachment.outerHTML,
-      intent: attachment.attachment.intent ?? null,
       comment: attachment.attachment.comment ?? null,
     });
   }