feat(core): rename string and stream functions for clarity

- Rename `cstring_push` to `cstring_append_ch` and `cstring_push_cstr` to `cstring_append_cstr` for consistent naming with new `cstring_append` function
- Update all callers in lexer and tests to use new function names
- Rename stream `destroy` method to `drop` for consistency with resource management conventions
- Fix potential overflow in string capacity calculation by adjusting growth logic

runtime/libcore/include/core_stream.h

@@ -46,7 +46,7 @@ struct core_probe_stream {
     cbool (*is_at_end)(core_probe_stream_t *stream);
 
     /// @brief 销毁流并释放资源
-    void (*destroy)(core_probe_stream_t *stream);
+    void (*drop)(core_probe_stream_t *stream);
 };
 
 static inline int core_probe_stream_consume(core_probe_stream_t *self) {
@@ -86,8 +86,8 @@ static inline cbool core_probe_stream_has_more(core_probe_stream_t *self) {
     return !self->is_at_end(self);
 }
 
-static inline void core_probe_stream_destroy(core_probe_stream_t *self) {
-    self->destroy(self);
+static inline void core_probe_stream_drop(core_probe_stream_t *self) {
+    self->drop(self);
 }
 
 #ifndef __SMCC_CORE_NO_MEM_PROBE_STREAM__