Server overhaul: sync push delete step in its own function; clap env feature dropped

process<K> (158 lines) hands step 7 against a stored row to delete_stored<K>; same SQL, audit and push. kvitt-server
never reads a clap argument from the environment (Config reads it), so clap's env feature goes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

server/crates/kvitt-server/Cargo.toml

@@ -21,7 +21,7 @@ axum = "0.8.9"
 base64 = "0.23.1"
 chrono = { version = "0.4.45", default-features = false, features = ["clock", "std"] }
 chrono-tz = "0.10.4"
-clap = { version = "4.6.7", features = ["derive", "env"] }
+clap = { version = "4.6.7", features = ["derive"] }
 getrandom = "0.4.3"
 image = { version = "0.25.10", default-features = false, features = ["jpeg", "png", "webp"] }
 jsonwebtoken = { version = "11.1.0", default-features = false, features = ["aws_lc_rs", "use_pem"] }