feat: integración completa de red P2P

- connection.zig: Reescrito con integración completa
  - NAT traversal (STUN + NAT-PMP/UPnP)
  - Discovery (local UDP + global HTTPS)
  - TCP listener para conexiones entrantes
  - Flujo completo de conexión: resolving -> connecting -> handshaking -> connected
  - Envío/recepción de mensajes con protocol framing
  - Gestión de direcciones (local, pública, relay)
  - Port mapping automático

- discovery.zig: Añadidos métodos de DiscoveryManager
  - startLocalDiscovery, stopLocalDiscovery
  - addGlobalServer, announceGlobal
  - addKnownPeer

- crypto.zig: Fix u128 cast para shifts > 64 bits
- http.zig: Fix ArrayListUnmanaged API para Zig 0.15.2

Tests: 44 (todos pasando)

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

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

CLAUDE.md

@@ -85,10 +85,10 @@ zcatp2p/
 - [x] Implementación discovery local (UDP broadcast)
 - [x] Implementación STUN client
 - [x] Implementación relay client
-- [x] Tests unitarios (41 tests)
+- [x] Tests unitarios (44 tests)
 - [x] Discovery global (HTTPS API)
 - [x] UPnP/NAT-PMP port mapping
-- [ ] Integración completa de red
+- [x] Integración completa de red
 
 ## Comandos
 

src/crypto.zig

@@ -456,7 +456,7 @@ pub const Poly1305 = struct {
 
         // Convertir a bytes
         var result: [16]u8 = undefined;
-        const full = h0 | (h1 << 44) | (h2 << 88);
+        const full: u128 = @as(u128, h0) | (@as(u128, h1) << 44) | (@as(u128, h2) << 88);
         std.mem.writeInt(u128, &result, full, .little);
         return result;
     }

src/discovery.zig

@@ -519,6 +519,39 @@ pub const DiscoveryManager = struct {
     ) void {
         self.on_device_discovered = cb;
     }
+
+    /// Inicia el discovery local
+    pub fn startLocalDiscovery(self: *DiscoveryManager, port: u16) !void {
+        self.local.local_port = port;
+        try self.local.start();
+    }
+
+    /// Detiene el discovery local
+    pub fn stopLocalDiscovery(self: *DiscoveryManager) void {
+        if (self.local.socket) |sock| {
+            std.posix.close(sock);
+            self.local.socket = null;
+        }
+    }
+
+    /// Añade un servidor de discovery global
+    pub fn addGlobalServer(self: *DiscoveryManager, server: []const u8) !void {
+        try self.global.addServer(server);
+    }
+
+    /// Anuncia direcciones en discovery global
+    pub fn announceGlobal(self: *DiscoveryManager, addresses: []const []const u8) !void {
+        try self.global.announce(addresses);
+    }
+
+    /// Añade direcciones conocidas para un peer
+    pub fn addKnownPeer(self: *DiscoveryManager, device_id: DeviceId, addresses: []const []const u8) !void {
+        // Añadir al cache local
+        _ = device_id;
+        for (addresses) |addr| {
+            try self.local.addAddress(addr);
+        }
+    }
 };
 
 // =============================================================================

src/http.zig

@@ -470,14 +470,15 @@ pub const HttpClient = struct {
         response.status_code = @enumFromInt(status_code);
 
         // Status text
-        var status_text_parts = std.ArrayList(u8).init(self.allocator);
+        var status_text_parts: std.ArrayListUnmanaged(u8) = .{};
+        defer status_text_parts.deinit(self.allocator);
         while (parts.next()) |part| {
             if (status_text_parts.items.len > 0) {
-                try status_text_parts.append(' ');
+                try status_text_parts.append(self.allocator, ' ');
             }
-            try status_text_parts.appendSlice(part);
+            try status_text_parts.appendSlice(self.allocator, part);
         }
-        response.status_text = try status_text_parts.toOwnedSlice();
+        response.status_text = try status_text_parts.toOwnedSlice(self.allocator);
 
         // Parsear headers
         const header_start = status_end + 2;