Add unit test suite and complete protocol documentation

- Add test framework (test.h) with assertion macros and test runner
- Add comprehensive unit tests (test_network.c) covering:
  - Packet parsing and error handling
  - User registration and authentication
  - Room operations (create, join, leave, delete, list)
  - Direct messaging functionality
  - Message broadcasting
  - Password hashing
- Update Makefile with 'make test' target
- Rewrite PROTOCOL file with complete specification:
  - All 14 packet types with data layouts
  - All error codes with descriptions
  - Typical usage flows

main.c

@@ -5,7 +5,9 @@
 #include <uv.h>
 #include <openssl/ssl.h>
 #include <openssl/err.h>
+#include "config.h"
 #include "client.h"
+#include "network.h"
 
 uv_loop_t *loop;
 SSL_CTX *ctx;
@@ -13,6 +15,7 @@ SSL_CTX *ctx;
 void cleanup_client(uv_handle_t *handle)
 {
 	struct client *client = (struct client*) handle;
+	network_client_remove(client);
 	if (client->ssl) {
 		SSL_free(client->ssl);
 	}
@@ -65,11 +68,11 @@ void on_read(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf)
 
 		char plain_buf[4096];
 		int p;
-		
+
 		while ((p = SSL_read(client->ssl, plain_buf, sizeof(plain_buf))) > 0) {
-			ssl_write_msg(client, plain_buf, p);
+			network_handle_data(client, plain_buf, p);
 		}
-		
+
 		flush_ssl_to_socket(client);
 	} 
 	else if (nread < 0) {
@@ -102,7 +105,13 @@ void on_new_connection(uv_stream_t *server, int status)
 		client->wbio = BIO_new(BIO_s_mem());
 		SSL_set_bio(client->ssl, client->rbio, client->wbio);
 		SSL_set_accept_state(client->ssl);
-		
+
+		client->user_id = 0;
+		client->current_room_id = 0;
+		client->is_authenticated = false;
+		client->username[0] = '\0';
+
+		network_client_add(client);
 		uv_read_start((uv_stream_t*) &client->handle, alloc_buffer, on_read);
 	} else {
 		uv_close((uv_handle_t*) &client->handle, cleanup_client);
@@ -132,6 +141,12 @@ void init_openssl()
 int main()
 {
 	init_openssl();
+
+	if (network_init() != 0) {
+		fprintf(stderr, "Failed to initialize network/database\n");
+		return 1;
+	}
+
 	loop = uv_default_loop();
 
 	uv_tcp_t server;