Cyper-axum huge performance degradation with Keep-Alive (HTTP 1?) connections

## Issue

I benchmarked axum+tokio(current thread flavor) and cyper-axum+compio with and without Keep-Alive.
The server is simple: return 64KiB of data (result verified by response document length).
For some reason, Keep-Alive connections causes HUGE RPS drop.

## Expected behavior

For any server for any case etc... Keep-Alive should improve performance due to connection caching.

## Actual behavior

Dealing with keep-alive connections causes 100X RPS drop.
While axum+tokio has 3X improvement

## My benchmark results

| Example | Keep-Alive | RPS | Command | Benchmark command |
| ----------------- | ---------- | -------- | -------------------------------------- | ------------------------------------------------ |
| axum+tokio | No | 16515.13 | cargo run --release --bin server-tokio | ab -c 4 -t 5 -n 100000 http://127.0.0.1:3000/ |
| axum+tokio | Yes | 51462.06 | cargo run --release --bin server-tokio | ab -k -c 4 -t 5 -n 100000 http://127.0.0.1:3000/ |
| cyper-axum+compio | No | 9789.98 | cargo run --release --bin server-cyper | ab -c 4 -t 5 -n 100000 http://127.0.0.1:3000/ |
| cyper-axum+compio | Yes | 98.27 | cargo run --release --bin server-cyper | ab -k -c 4 -t 5 -n 100000 http://127.0.0.1:3000/ |

## Steps to reproduce

+ Clone repository: https://github.com/inklesspen1rus/cyper-axum-issue
+ Run server using command from benchmark results (for axum+tokio: cargo run --release --bin server-tokio )
+ Run benchmark command from benchmark results (for Keep-Alive=Yes: ab -k -c 4 -t 5 -n 100000 http://127.0.0.1:3000/)

### Environment
```
rustc 1.90.0-nightly (706f244db 2025-06-23)
cargo 1.90.0-nightly (84709f085 2025-06-22)
nightly-x86_64-unknown-linux-gnu
```

```
OS: Manjaro Linux x86_64
Host: B550 AORUS ELITE V2
Kernel: 6.15.8-1-MANJARO
Uptime: 5 hours, 28 mins
Packages: 2010 (pacman), 29 (flatpak), 11 (snap)
Shell: bash 5.3.3
Resolution: 1920x1080
DE: Plasma 6.4.3
WM: kwin
Theme: Breath Dark [Plasma], Breeze-Dark [GTK2], Breeze [GTK3]
Icons: breeze [Plasma], breeze [GTK2/3]
Terminal: vscode
CPU: AMD Ryzen 5 5600 (12) @ 4.470GHz
GPU: NVIDIA GeForce GTX 1060 6GB
Memory: 19931MiB / 32010MiB
```