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/lib/daresApi.ts

@@ -13,7 +13,11 @@ export const daresApi = {
     send: (payload: SendDarePayload) => apiClient.post<{ dare: SentDare }>("/v1/dares", payload),
     respond: (dareId: string, action: "accept" | "decline") =>
         apiClient.post<{ dare: SentDare }>(`${dare(dareId)}/respond`, { action }),
-    submit: (dareId: string) => apiClient.post<{ dare: SentDare }>(`${dare(dareId)}/submit`),
+    submit: (dareId: string, proofMediaId?: string) =>
+        apiClient.post<{ dare: SentDare }>(
+            `${dare(dareId)}/submit`,
+            proofMediaId ? { proof_media_id: proofMediaId } : undefined,
+        ),
     complete: (dareId: string) => apiClient.post<{ dare: SentDare }>(`${dare(dareId)}/complete`),
     cancel: (dareId: string) => apiClient.post<{ dare: SentDare }>(`${dare(dareId)}/cancel`),
 };

apps/mobile/src/lib/mediaApi.ts

@@ -3,7 +3,7 @@ import * as FileSystem from 'expo-file-system/legacy';
 import { decode } from 'base64-arraybuffer';
 import { ApiError, apiClient, authenticatedFetch } from './apiClient';
 
-export type MediaKind = 'avatar' | 'response' | 'chat' | 'feedback';
+export type MediaKind = 'avatar' | 'response' | 'chat' | 'feedback' | 'dare_proof';
 export interface UploadMediaOptions { kind: MediaKind; mimeType: string; questionId?: string; matchId?: string }
 export interface MediaUploadResponse { reference: string; media: { id: string; mime_type: string; byte_size: number }; message?: Record<string, unknown> }