feat(c-miner): port miner pipeline to modular C implementation

types.h

@@ -0,0 +1,26 @@
+#ifndef TYPES_H
+#define TYPES_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+typedef struct {
+    char hash[65];
+    char *data;
+} TemplateTransaction;
+
+typedef struct {
+    int version;
+    char previous_block_hash[65];
+    int curtime;
+    char bits[9];
+    int height;
+    uint64_t coinbase_value;
+    char *default_witness_commitment;
+    TemplateTransaction *transactions;
+    size_t tx_count;
+} BlockTemplate;
+
+void block_template_free(BlockTemplate *tpl);
+
+#endif