feat(yedek): JSON tam hane yedeği backend (önizleme, geri yükleme, geri dönüş noktaları)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/Cargo.toml

@@ -8,12 +8,14 @@ argon2 = "0.6.0"
 axum = "0.8.9"
 axum-extra = { version = "0.12.6", features = ["cookie"] }
 dotenvy = "0.15.7"
+flate2 = "1"
 jsonwebtoken = { version = "11.1.0", default-features = false, features = ["rust_crypto"] }
 mongodb = "3.10.0"
 quick-xml = { version = "0.42.0", features = ["serialize"] }
 reqwest = { version = "0.12", default-features = false, features = ["rustls-tls", "json"] }
 serde = { version = "1.0.229", features = ["derive"] }
 serde_json = "1.0.154"
+sha2 = "0.10"
 thiserror = "2.0.21"
 time = "0.3.55"
 tokio = { version = "1.54.1", features = ["full"] }