feat: update linker script to keep `.debug_line` section and adjust __eh_frame provision in linker script

Support virtual memory debugging by use better linking script. Reverts #7

Fix debugging with virtual memory enabled

Setup high-half virtual memory for kernel space

* test: add test scripts for system calls

* feat: add visualization script for test results

* test: add `sdcard.img` binary

* feat: add Makefile for contest submission and testing environment

* chore: update .gitignore to exclude test artifacts and logs

* fix: update paths for test runner and visualization scripts in Makefile

* fix: remove unnecessary strip step from build process in Makefile

* fix: prevent Makefile clean command from failing on missing files

* feat: add preliminary grading workflow for CI

* fix: update Makefile to fix path issue

* feat: add README for preliminary test artifacts and visualizer script

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Co-authored-by: The most intelligent Cirno <9@caiyi1.me>

Escape from `actions-rs/toolchain`

Add cache layer for `cargo-binutils` installation

Fix kernel code quality issue