feat(ir2mcode): 添加IR到机器码转换功能并修复函数命名

添加了完整的scc_ir2mcode实现，将MIR指令转换为机器码，
同时修复了头文件中的函数命名错误（scc_mir2sccf改为scc_ir2sccf）。

BREAKING CHANGE: 函数名从scc_mir2sccf更改为scc_ir2sccf

fix(vec): 修复向量循环和内存释放问题

修改了scc_vec_foreach宏使用+= 1避免潜在的编译器警告，
并添加了空指针检查以防止重复释放内存导致的崩溃。

refactor(hashtable): 优化哈希表接口设计

将scc_hashtable_get参数改为const类型，提供更好的只读访问安全性。

test: 添加break/continue和goto语句测试用例

新增18_break_continue.c和19_goto.c测试用例，
并对齐expect.toml文件格式以便于维护。

tests/simple/expect.toml

@@ -2,22 +2,24 @@
 # windows powershell: echo $LASTEXITCODE
 # nushell: echo $env.LAST_EXIT_CODE
 # bash: echo $?
-"./return_val_cases/01_return.c" = 65536
-"./return_val_cases/02_decl_expr.c" = 1
-"./return_val_cases/03_decl_init.c" = 11
-"./return_val_cases/04_if.c" = 1
-"./return_val_cases/05_else.c" = 2
-"./return_val_cases/06_fcall.c" = 3
-"./return_val_cases/07_while.c" = 10
-"./return_val_cases/08_do_while.c" = 128
-"./return_val_cases/09_for.c" = 10
-"./return_val_cases/10_main.c" = 3
-"./return_val_cases/11_recursive.c" = 120
-"./return_val_cases/12_logic.c" = 10
-"./return_val_cases/13_array.c" = 1198
-"./return_val_cases/14_pointer.c" = 2
+"./return_val_cases/01_return.c"          = 65536
+"./return_val_cases/02_decl_expr.c"       = 1
+"./return_val_cases/03_decl_init.c"       = 11
+"./return_val_cases/04_if.c"              = 1
+"./return_val_cases/05_else.c"            = 2
+"./return_val_cases/06_fcall.c"           = 3
+"./return_val_cases/07_while.c"           = 10
+"./return_val_cases/08_do_while.c"        = 128
+"./return_val_cases/09_for.c"             = 10
+"./return_val_cases/10_main.c"            = 3
+"./return_val_cases/11_recursive.c"       = 120
+"./return_val_cases/12_logic.c"           = 10
+"./return_val_cases/13_array.c"           = 1198
+"./return_val_cases/14_pointer.c"         = 2
 "./return_val_cases/15_array_subscript.c" = 1198
-"./return_val_cases/16_enum.c" = 5
-"./return_val_cases/17_more_arg.c" = 45
+"./return_val_cases/16_enum.c"            = 5
+"./return_val_cases/17_more_arg.c"        = 45
+"./return_val_cases/18_break_continue.c"  = 676
+"./return_val_cases/19_goto.c"            = 676
 [stdout_val_cases]
 "./stdout_val_cases/01_include.c" = "Hello World!\n"