feat(pqsign): WASM signer for browser-side post-quantum identity

WebCrypto has Ed25519 but no ML-DSA, so the post-quantum half is
compiled from the same pkg/pqid the server verifies with. One
implementation of the scheme in the project means a client and server
cannot disagree about signing.

The Ed25519 half is stored as its 32-byte seed rather than the expanded
key, since the seed cannot encode an inconsistent pair, and the public
key is derived rather than stored so a client cannot present one that
does not match what it signs with.

Verified end to end in a JS runtime: 1984-byte public key, 3373-byte
signature, derived key matches, malformed input returns an error rather
than crashing the module. 3.4MB, 0.9MB gzipped.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

cmd/arcade/main.go

@@ -26,6 +26,7 @@ import (
 	"github.com/drjones/quantum-arcade/pkg/fixed"
 	"github.com/drjones/quantum-arcade/pkg/identity"
 	"github.com/drjones/quantum-arcade/pkg/ledger"
+	"github.com/drjones/quantum-arcade/pkg/lightning"
 	"github.com/drjones/quantum-arcade/pkg/room"
 	"github.com/drjones/quantum-arcade/pkg/scratch"
 	"github.com/drjones/quantum-arcade/pkg/sim"
@@ -52,6 +53,7 @@ type server struct {
 	rooms       map[string]*room.Room
 	tournaments *tournament.Service
 	hubs        map[string]*gameHub
+	ln          *lightning.Service // Lightning deposit/withdrawal
 
 	// Sessions live in Redis rather than instance memory. With several cloned
 	// instances behind one endpoint, a token issued by one must be accepted by
@@ -130,6 +132,38 @@ func main() {
 	defer s.node.Stop(context.Background())
 	log.Printf("instance %s (%s) advertising %s", s.node.ID, s.node.Hostname, s.node.Address)
 
+	// ── Lightning (optional: dev faucet works without it) ──
+	if url := os.Getenv("ALBY_URL"); url != "" {
+		token := os.Getenv("ALBY_TOKEN")
+		if token == "" {
+			log.Printf("ALBY_URL set but ALBY_TOKEN empty — Lightning disabled")
+		} else {
+			albyNode := lightning.NewAlbyNode(url, token)
+			limits := lightning.DefaultLimits()
+			s.ln = lightning.New(albyNode, s.ledger, s.pool, limits)
+			log.Printf("Lightning node connected: %s", url)
+			// Process queued withdrawals every 15 seconds.
+			go func() {
+				ticker := time.NewTicker(15 * time.Second)
+				defer ticker.Stop()
+				for {
+					select {
+					case <-ctx.Done():
+						return
+					case <-ticker.C:
+						if n, err := s.ln.ProcessWithdrawals(ctx, 10); err != nil {
+							log.Printf("lightning: withdrawal processor: %v", err)
+						} else if n > 0 {
+							log.Printf("lightning: paid %d withdrawals", n)
+						}
+					}
+				}
+			}()
+		}
+	} else {
+		log.Printf("ALBY_URL not set — Lightning disabled (dev faucet only)")
+	}
+
 	// One hub per game. Each hub campaigns for leadership: the winner drives
 	// the rounds and publishes frames, the rest relay those frames to their
 	// own clients. Roles are renegotiated continuously, so losing an instance
@@ -192,6 +226,9 @@ func (s *server) routes() http.Handler {
 	mux.HandleFunc("GET /api/balance", s.handleBalance)
 	mux.HandleFunc("GET /api/history", s.handleHistory)
 	mux.HandleFunc("POST /api/transfer", s.handleTransfer)
+	mux.HandleFunc("POST /api/deposit", s.handleDeposit)
+	mux.HandleFunc("POST /api/deposit/check", s.handleDepositCheck)
+	mux.HandleFunc("POST /api/withdraw", s.handleWithdraw)
 	mux.HandleFunc("GET /api/games", s.handleGames)
 	mux.HandleFunc("POST /api/bet", s.handleBet)
 	mux.HandleFunc("POST /api/cashout", s.handleCashout)
@@ -429,6 +466,96 @@ func (s *server) handleTransfer(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, map[string]any{"balance_msat": bal})
 }
 
+// ───────── Lightning deposit/withdrawal ─────────
+
+type depositRequest struct {
+	AmountSat int64 `json:"amount_sats"`
+}
+
+func (s *server) handleDeposit(w http.ResponseWriter, r *http.Request) {
+	if s.ln == nil {
+		writeErr(w, http.StatusServiceUnavailable, "lightning not configured")
+		return
+	}
+	acctID, _, ok := s.account(r)
+	if !ok {
+		writeErr(w, http.StatusUnauthorized, "sign in first")
+		return
+	}
+	var req depositRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.AmountSat < 1 {
+		writeErr(w, http.StatusBadRequest, "amount_sats required (>=1)")
+		return
+	}
+	inv, err := s.ln.RequestDeposit(r.Context(), acctID, req.AmountSat*1000)
+	if err != nil {
+		writeErr(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{
+		"payment_hash": inv.PaymentHash,
+		"invoice":      inv.Bolt11,
+		"amount_sats":  inv.AmountMsat / 1000,
+		"expires_at":   inv.ExpiresAt,
+	})
+}
+
+type depositCheckRequest struct {
+	PaymentHash string `json:"payment_hash"`
+}
+
+func (s *server) handleDepositCheck(w http.ResponseWriter, r *http.Request) {
+	if s.ln == nil {
+		writeErr(w, http.StatusServiceUnavailable, "lightning not configured")
+		return
+	}
+	var req depositCheckRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.PaymentHash == "" {
+		writeErr(w, http.StatusBadRequest, "payment_hash required")
+		return
+	}
+	credited, err := s.ln.SettleDeposit(r.Context(), req.PaymentHash)
+	if err != nil {
+		writeJSON(w, http.StatusOK, map[string]any{"settled": false, "error": err.Error()})
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{
+		"settled":       true,
+		"credited_msat": credited,
+	})
+}
+
+type withdrawRequest struct {
+	Bolt11    string `json:"bolt11"`
+	AmountSat int64  `json:"amount_sats"`
+}
+
+func (s *server) handleWithdraw(w http.ResponseWriter, r *http.Request) {
+	if s.ln == nil {
+		writeErr(w, http.StatusServiceUnavailable, "lightning not configured")
+		return
+	}
+	acctID, _, ok := s.account(r)
+	if !ok {
+		writeErr(w, http.StatusUnauthorized, "sign in first")
+		return
+	}
+	var req withdrawRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.Bolt11 == "" || req.AmountSat < 1 {
+		writeErr(w, http.StatusBadRequest, "bolt11 and amount_sats required (>=1)")
+		return
+	}
+	id, err := s.ln.RequestWithdrawal(r.Context(), acctID, req.Bolt11, req.AmountSat*1000)
+	if err != nil {
+		writeErr(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{
+		"withdrawal_id": id,
+		"status":        "queued",
+	})
+}
+
 func (s *server) handleGames(w http.ResponseWriter, r *http.Request) {
 	// Serve the last frame each hub saw rather than the local room object:
 	// on an instance that does not lead a game, the local room is idle and