fix: remove redundant .bss zeroing that destroyed page tables

Co-authored-by: aider (openrouter/moonshotai/kimi-k2.6) <aider@aider.chat>

kernel_entry.S

@@ -83,12 +83,6 @@ long_mode_start:
     movabsq $stack_top, %rax
     movq %rax, %rsp
 
-    movabsq $__bss_start, %rdi
-    movabsq $__bss_end, %rcx
-    subq %rdi, %rcx
-    xorq %rax, %rax
-    rep stosb
-
     call kernel_main
     cli
 1:

platform_kernel.c

@@ -137,6 +137,7 @@ void forth_printf(const char* fmt, ...) {
 
 void kernel_main(void) {
     serial_init();
+    forth_printf("Kernel started\n");
     forth_run();
     forth_panic();
 }