Add WireGuard VPN with random /31 subnet isolation (v0.40.0)

- Add embedded WireGuard VPN server using wireguard-go + netstack
- Implement deterministic /31 subnet allocation from seed + sequence
- Use Badger's built-in Sequence for atomic counter allocation
- Add NIP-46 bunker server for remote signing over VPN
- Add revoked key tracking and access audit logging for users
- Add Bunker tab to web UI with WireGuard/bunker QR codes
- Support key regeneration with old keypair archiving

New environment variables:
- ORLY_WG_ENABLED: Enable WireGuard VPN server
- ORLY_WG_PORT: UDP port for WireGuard (default 51820)
- ORLY_WG_ENDPOINT: Public endpoint for WireGuard
- ORLY_WG_NETWORK: Base network for subnet pool (default 10.0.0.0/8)
- ORLY_BUNKER_ENABLED: Enable NIP-46 bunker
- ORLY_BUNKER_PORT: WebSocket port for bunker (default 3335)

Files added:
- pkg/wireguard/: WireGuard server, keygen, subnet pool, errors
- pkg/bunker/: NIP-46 bunker server and session handling
- pkg/database/wireguard.go: Peer storage with audit logging
- app/handle-wireguard.go: API endpoints for config/regenerate/audit
- app/wireguard-helpers.go: Key derivation helpers
- app/web/src/BunkerView.svelte: Bunker UI with QR codes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkg/wireguard/keygen.go

@@ -0,0 +1,42 @@
+// Package wireguard provides an embedded WireGuard VPN server for secure
+// NIP-46 bunker access. It uses wireguard-go with gVisor netstack for
+// userspace networking (no root required).
+package wireguard
+
+import (
+	"crypto/rand"
+
+	"golang.org/x/crypto/curve25519"
+)
+
+// GenerateKeyPair generates a new Curve25519 keypair for WireGuard.
+// Returns the private key and public key as 32-byte slices.
+func GenerateKeyPair() (privateKey, publicKey []byte, err error) {
+	privateKey = make([]byte, 32)
+	if _, err = rand.Read(privateKey); err != nil {
+		return nil, nil, err
+	}
+
+	// Curve25519 clamping (required by WireGuard spec)
+	privateKey[0] &= 248
+	privateKey[31] &= 127
+	privateKey[31] |= 64
+
+	// Derive public key from private key
+	publicKey = make([]byte, 32)
+	curve25519.ScalarBaseMult((*[32]byte)(publicKey), (*[32]byte)(privateKey))
+
+	return privateKey, publicKey, nil
+}
+
+// DerivePublicKey derives the public key from a private key.
+func DerivePublicKey(privateKey []byte) (publicKey []byte, err error) {
+	if len(privateKey) != 32 {
+		return nil, ErrInvalidKeyLength
+	}
+
+	publicKey = make([]byte, 32)
+	curve25519.ScalarBaseMult((*[32]byte)(publicKey), (*[32]byte)(privateKey))
+
+	return publicKey, nil
+}