feat(parser): 启用parser和ast模块并重构解析器结构

- 在cbuild.toml中启用parser和ast依赖项
- 将AST内置类型枚举重命名为SCC_AST_BUILTIN_TYPE_*前缀格式
- 修复ast_def.h中的类型字段命名，将builtin改为type
- 添加逗号操作符支持到表达式操作符枚举中
- 更新字面量表达式的lexeme字段为const char*指针和owned标志
- 重构解析器头文件结构，分离为parser.h、parser_utils.h、scc_sema.h等
- 实现新的解析器工具函数，包括预览、消费、回溯等功能
- 更新声明解析逻辑，使用新的解析器接口进行token处理
- 添加符号表语义分析功能框架
- 修复词法分析器中token移动时的空指针检查
- 统一使用scc_tree_dump_printf替代直接的scc_printf调用

libs/parser/src/scc_parser.c

@@ -0,0 +1,82 @@
+#include <parser_utils.h>
+#include <scc_parser.h>
+static void dummy_sema_callback(void *context, scc_ast_node_type_t node_type,
+                                void *node) {
+    (void)context;
+    (void)node_type;
+    (void)node;
+    return;
+}
+
+#define ASSIGN_PTR_OR_DEFAULT(assigned_val, value, default)                    \
+    assigned_val = value ? value : default
+
+void scc_parser_init(scc_parser_t *parser, scc_lexer_tok_ring_t *tok_ring,
+                     scc_sema_callbacks_t *callbacks) {
+    Assert(parser != null && tok_ring != null);
+    parser->ring = tok_ring;
+    parser->errcode = 0;
+    parser->translation_unit = null;
+    if (callbacks) {
+        ASSIGN_PTR_OR_DEFAULT(parser->sema_callbacks.on_decl,
+                              callbacks->on_decl, dummy_sema_callback);
+        ASSIGN_PTR_OR_DEFAULT(parser->sema_callbacks.on_stmt,
+                              callbacks->on_stmt, dummy_sema_callback);
+        ASSIGN_PTR_OR_DEFAULT(parser->sema_callbacks.on_expr,
+                              callbacks->on_expr, dummy_sema_callback);
+        ASSIGN_PTR_OR_DEFAULT(parser->sema_callbacks.on_type,
+                              callbacks->on_type, dummy_sema_callback);
+        parser->sema_callbacks.context = callbacks->context;
+    } else {
+        parser->sema_callbacks.on_decl = dummy_sema_callback;
+        parser->sema_callbacks.on_stmt = dummy_sema_callback;
+        parser->sema_callbacks.on_expr = dummy_sema_callback;
+        parser->sema_callbacks.on_type = dummy_sema_callback;
+        parser->sema_callbacks.context = null;
+    }
+}
+
+void scc_parser_drop(scc_parser_t *parser) {
+    // TODO: 释放 AST 内存
+}
+
+scc_ast_translation_unit_t *scc_parse_translation_unit(scc_parser_t *parser) {
+    scc_ast_translation_unit_t *unit =
+        scc_malloc(sizeof(scc_ast_translation_unit_t));
+    if (!unit)
+        return null;
+    unit->base.type = SCC_AST_TRANSLATION_UNIT;
+    scc_vec_init(unit->declarations);
+
+    /**
+     * Program := (Declaration | Definition)*
+     * same as
+     * Program := Declaration* Definition*
+     */
+    cbool matched = false;
+    while (1) {
+        scc_ast_decl_t *decl = scc_parse_declaration(parser);
+        if (decl != null) {
+            scc_vec_push(unit->declarations, decl);
+        } else {
+            break;
+            // MAYBE return or next
+        }
+        if (parser->errcode != 0) { // FIXME errcode
+            break;
+        }
+        const scc_lexer_tok_t *tok = scc_parser_peek(parser);
+        if (tok == null || tok->type == SCC_TOK_EOF) {
+            break;
+        }
+    }
+
+    if (parser->errcode) {
+        // TODO: 清理
+        scc_free(unit);
+        return null;
+    }
+
+    Assert(unit->base.type == SCC_AST_TRANSLATION_UNIT);
+    return unit;
+}