feat(lex_parser): rename functions and update header guard prefix

- Change header guard from `__SMCC_LEX_PARSER_H__` to `__SCC_LEX_PARSER_H__`
- Prefix all lexer functions with `scc_` (e.g., `lex_parse_char` → `scc_lex_parse_char`)
- Add new helper function `scc_lex_parse_is_identifier_header`
- Update references in source and test files to use new function names
- Replace `core_stream_eof` with `scc_stream_eof` for consistency

runtime/libcore/src/stream.c

@@ -8,7 +8,7 @@ static int mem_probe_stream_consume(scc_probe_stream_t *_stream) {
     scc_mem_probe_stream_t *stream = (scc_mem_probe_stream_t *)_stream;
 
     if (stream->curr_pos >= stream->data_length) {
-        return core_stream_eof;
+        return scc_stream_eof;
     }
 
     unsigned char ch = stream->data[stream->curr_pos++];
@@ -24,7 +24,7 @@ static int mem_probe_stream_peek(scc_probe_stream_t *_stream) {
     scc_mem_probe_stream_t *stream = (scc_mem_probe_stream_t *)_stream;
 
     if (stream->probe_pos >= stream->data_length) {
-        return core_stream_eof;
+        return scc_stream_eof;
     }
 
     // 只查看而不移动探针位置
@@ -36,7 +36,7 @@ static int mem_probe_stream_next(scc_probe_stream_t *_stream) {
     scc_mem_probe_stream_t *stream = (scc_mem_probe_stream_t *)_stream;
 
     if (stream->probe_pos >= stream->data_length) {
-        return core_stream_eof;
+        return scc_stream_eof;
     }
 
     // 返回探针位置的字符，并将探针位置向前移动