Stream post videos to Spaces (#23)

Pass the spooled video file through instead of buffering it in RAM, and sign Spaces uploads as UNSIGNED-PAYLOAD so the client does not hash the body first.

Reviewed-on: #23
Co-authored-by: codegirl-007 <s.raide@gmail.com>

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/aws/aws-sdk-go-v2 v1.43.7
 	github.com/aws/aws-sdk-go-v2/credentials v1.19.37
 	github.com/aws/aws-sdk-go-v2/service/s3 v1.107.3
+	github.com/aws/smithy-go v1.27.8
 	github.com/bwmarrin/discordgo v0.29.0
 	github.com/go-chi/chi/v5 v5.3.1
 	github.com/google/uuid v1.6.0
@@ -27,7 +28,6 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/internal/checksum v1.9.31 // indirect
 	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.13.38 // indirect
 	github.com/aws/aws-sdk-go-v2/service/internal/s3shared v1.19.39 // indirect
-	github.com/aws/smithy-go v1.27.8 // indirect
 	github.com/gorilla/websocket v1.4.2 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect