migrate to sqlite

NOTE: extension loading crashes docker (for some reason)

backend/Cargo.toml

@@ -13,7 +13,7 @@ path = "src/bin/backend/main.rs"
 
 [dependencies]
 anyhow = "1.0.98"
-argon2 = "0.5.3"
+argon2 = { version = "0.5.3", features = ["std"] }
 axum = { version = "0.8.4", features = ["multipart", "query"] }
 axum-extra = { version = "0.10.1", features = ["cookie", "multipart"] }
 base64 = "0.22.1"
@@ -29,13 +29,7 @@ regex = "1.11.1"
 rustix = { version = "1.0.8", features = ["fs"] }
 serde = { version = "1.0.219", features = ["derive"] }
 serde_json = "1.0.140"
-sqlx = { version = "0.8.6", features = [
-	"chrono",
-	"postgres",
-	"runtime-tokio",
-	"time",
-	"uuid",
-] }
+sqlx = { version = "0.8.6", features = ["chrono", "runtime-tokio", "sqlite", "time", "uuid"] }
 thiserror = "2.0.12"
 tokio = { version = "1.46.1", features = ["full"] }
 tokio-stream = "0.1.17"