feat(dares): optional photo/audio proof of completion

The sender can require photo or audio proof when sending any dare,
catalogue or custom. The recipient captures and uploads the proof as a
new couple-scoped 'dare_proof' media kind and attaches it on submit;
the server enforces ownership, kind, couple, and MIME-type match.
The proof renders inline on the dare card for the sender to review
before confirming completion.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/mobile/src/features/dares/components/index.ts

@@ -4,3 +4,7 @@ export { DarePackGrid } from "./DarePackGrid";
 export type { DarePackGridProps } from "./DarePackGrid";
 export { SendDareSheet } from "./SendDareSheet";
 export type { SendDareSheetProps } from "./SendDareSheet";
+export { DareProofSheet } from "./DareProofSheet";
+export type { DareProofSheetProps } from "./DareProofSheet";
+export { DareProofView } from "./DareProofView";
+export type { DareProofViewProps } from "./DareProofView";