feat(lex_parser, pprocessor): rename identifier header check and add macro system

- Rename `scc_lex_parse_is_identifier_header` to `scc_lex_parse_is_identifier_prefix` for clarity and add a TODO comment
- Update lexer to use the renamed function for consistency
- Fix package and dependency names in `cbuild.toml` (`smcc_pprocesser` → `scc_pprocesser`, `smcc_lex_parser` → `lex_parser`)
- Introduce new macro system with header file `pp_macro.h` defining macro types, structures, and management functions
- Refactor preprocessor initialization and cleanup in `pprocessor.c` to use new macro table and stream handling
- Replace legacy `hashmap` with `scc_pp_macro_table_t` for macro storage
- Improve error handling and resource management in preprocessor lifecycle

runtime/libcore/include/core_str.h

@@ -136,7 +136,13 @@ static inline void scc_cstring_append_ch(scc_cstring_t *str, char ch) {
  * @return usize 字符串实际长度
  */
 static inline usize scc_cstring_len(const scc_cstring_t *str) {
-    return str ? str->size - 1 : 0;
+    if (str == null) {
+        return 0;
+    }
+    if (str->size == 0) {
+        return 0;
+    }
+    return str->size - 1;
 }
 
 /**