use an env var for configurable proxy header (#8863)

src/lib/constants.ts

@@ -1,6 +1,9 @@
 import {type Insets, Platform} from 'react-native'
 import {type AppBskyActorDefs} from '@atproto/api'
 
+import {type ProxyHeaderValue} from '#/state/session/agent'
+import {BLUESKY_PROXY_DID, CHAT_PROXY_DID} from '#/env'
+
 export const LOCAL_DEV_SERVICE =
   Platform.OS === 'android' ? 'http://10.0.2.2:2583' : 'http://localhost:2583'
 export const STAGING_SERVICE = 'https://staging.bsky.dev'
@@ -211,6 +214,16 @@ export const PUBLIC_STAGING_APPVIEW_DID = 'did:web:api.staging.bsky.dev'
 
 export const DEV_ENV_APPVIEW = `http://localhost:2584` // always the same
 
+export const BLUESKY_PROXY_HEADER: ProxyHeaderValue = `${BLUESKY_PROXY_DID}#bsky_appview`
+
+export const BLUESKY_SERVICE_HEADERS = {
+  'atproto-proxy': BLUESKY_PROXY_HEADER,
+}
+
+export const DM_SERVICE_HEADERS = {
+  'atproto-proxy': `${CHAT_PROXY_DID}#bsky_chat`,
+}
+
 export const webLinks = {
   tos: `https://bsky.social/about/support/tos`,
   privacy: `https://bsky.social/about/support/privacy-policy`,