build: add Makefile and C runtime configuration files

miner.conf.example

@@ -0,0 +1,23 @@
+# RPC
+RPC_USER=regtest
+RPC_PASSWORD=regtest
+RPC_HOST=127.0.0.1
+RPC_PORT=18443
+
+# Wallet
+WALLET_ADDRESS=bcrt1qn9ewln06n3xmc64278nj8m4nyde7ddeuvsvhw6
+
+# Mining
+DIFFICULTY_FACTOR=0.01
+NONCE_MODE=incremental   # incremental | random | mixed
+TIMESTAMP_UPDATE_INTERVAL=30
+BATCH=10000
+COINBASE_MESSAGE=/c-miner/
+EXTRANONCE1=1234567890abcdef
+EXTRANONCE2=12341234
+
+# Workers
+NUM_PROCESSORS=0         # <=0 uses CPU count
+
+# Watchdog
+CHECK_INTERVAL=20