Add chunked uploads and raise storage rate to GHS 0.30/GB/month.

Large files upload in 5 MB chunks (hosting file manager pattern) for the
transfer UI and Ladill Mail S2S API, with no app-level file size cap when
TRANSFER_MAX_FILE_BYTES=0.

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

deploy/shared.env.example

@@ -37,8 +37,8 @@ BILLING_API_KEY_TRANSFER=
 IDENTITY_API_URL=https://ladill.com/api
 IDENTITY_API_KEY_TRANSFER=
 
-TRANSFER_PRICE_PER_GB_MONTH=0.15
-TRANSFER_MAX_FILE_BYTES=524288000
+TRANSFER_PRICE_PER_GB_MONTH=0.30
+TRANSFER_MAX_FILE_BYTES=0
 TRANSFER_MAX_FILES=20
 TRANSFER_DEFAULT_RETENTION_DAYS=30
 TRANSFER_MAIL_RETENTION_DAYS=30