Complete private Monero miner control stack.

Implement Windows agent with RandomX mining and WebSocket fleet reporting, wire dashboard settings into the builder with saved exe paths, and add project README.

agent/miner/engine.go

@@ -0,0 +1,65 @@
+package miner
+
+import (
+	"encoding/hex"
+	"sync"
+
+	"git.gammaspectra.live/P2Pool/go-randomx"
+)
+
+const nonceOffset = 39
+const nonceSize = 4
+
+type Engine struct {
+	mu        sync.RWMutex
+	cache     *randomx.Randomx_Cache
+	vm        *randomx.VM
+	seedHex   string
+	blob      []byte
+}
+
+func NewEngine() *Engine {
+	cache := randomx.Randomx_alloc_cache(0)
+	return &Engine{cache: cache}
+}
+
+func (e *Engine) SetJob(seedHex, blobHex string) error {
+	seed, err := hex.DecodeString(seedHex)
+	if err != nil {
+		return err
+	}
+	blob, err := hex.DecodeString(blobHex)
+	if err != nil {
+		return err
+	}
+
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	if e.seedHex != seedHex {
+		e.cache.Randomx_init_cache(seed)
+		e.vm = e.cache.VM_Initialize()
+		e.seedHex = seedHex
+	}
+	e.blob = append([]byte(nil), blob...)
+	return nil
+}
+
+func (e *Engine) HashAtNonce(nonce uint32) (hashHex string, blobHex string, err error) {
+	e.mu.RLock()
+	defer e.mu.RUnlock()
+
+	if e.vm == nil || len(e.blob) < nonceOffset+nonceSize {
+		return "", "", nil
+	}
+
+	work := append([]byte(nil), e.blob...)
+	work[nonceOffset] = byte(nonce)
+	work[nonceOffset+1] = byte(nonce >> 8)
+	work[nonceOffset+2] = byte(nonce >> 16)
+	work[nonceOffset+3] = byte(nonce >> 24)
+
+	out := make([]byte, 32)
+	e.vm.CalculateHash(work, out)
+	return hex.EncodeToString(out), hex.EncodeToString(work), nil
+}