cleanup: remove dead code, fix bugs, refactor SSH dest parsing

- Remove debug printf calls from file.c
- Remove dead code: chunk_print, chunk_format, chunk_data_create/delete
- Remove unused config.use_single_send_per_file field
- Fix server_delete() no-op (double-pointer)
- Fix double cast (long)(long) -> ptrdiff_t in chunk.c
- Fix thread return value: thrd_error instead of 1
- Remove unused config param from receive_chunk_enqueue()
- Make queue_double_capacity() static
- Move SSH dest parsing into config.c as config_parse_ssh_dest()
- Fix test_config_ssh_dest to test parsing round-trip
- Remove chunk_format test (obsolete format)
- Replace chunk_data_delete with data_destroy in tests

src/shared/chunk.h

@@ -15,13 +15,10 @@ typedef struct {
 
 Chunk *chunk_create(File **items, int element_count);
 void chunk_destroy(void *chunk);
-void chunk_print(void *chunk);
-Data *chunk_format(Chunk *chunk);
 Data *chunk_serialize(Chunk *chunk, bool use_metadata);
 Chunk *chunk_deserialize(Data *data, bool use_metadata);
 Data *chunk_compress(Chunk *chunk, int compression_level, bool use_metadata);
 Chunk *chunk_decompress(Data *compressed_data, bool use_metadata);
 
-Data *chunk_data_create(void *data, unsigned long long data_size);
-void chunk_data_delete(void *chunk);
+
 #endif