Add handshake/stream encryption RPC commands

Replace protocol.encryption.set bitmask flags with
protocol.encryption.handshake.set and protocol.encryption.stream.set.
Add encryption_config to map commands to libtorrent EncryptionPolicy.
Startup default matches the old preset (allow_incoming, enable_retry,
prefer_plaintext → handshake=allow, stream=allow).

Update docs and examples. Peer list distinguishes RC4 (R/L),
handshake-only (H/h), and plain (r/l). Fix ui encrypted column
conditional. Add encryption config tests; remove OPTION_ENCRYPTION
parse tests. Drop the encryption command redirect.

test/src/test_encryption_config.cc

@@ -0,0 +1,45 @@
+#include "config.h"
+
+#include "test/src/test_encryption_config.h"
+
+#include <torrent/runtime/encryption_policy.h>
+
+#include "encryption_config.h"
+
+CPPUNIT_TEST_SUITE_REGISTRATION(TestEncryptionConfig);
+
+void
+TestEncryptionConfig::test_default_policy() {
+  const auto policy = encryption_config::default_policy();
+
+  CPPUNIT_ASSERT(policy.handshake == encryption_config::Policy::Mode::allow);
+  CPPUNIT_ASSERT(policy.stream == encryption_config::Policy::Mode::allow);
+
+  CPPUNIT_ASSERT_EQUAL(std::string("handshake=allow stream=allow"),
+                       encryption_config::summary_string(policy));
+}
+
+void
+TestEncryptionConfig::test_granular_round_trip() {
+  auto round_trip_handshake = [](const std::string& value) {
+    encryption_config::Policy policy;
+    encryption_config::apply_mode_value(policy, &encryption_config::Policy::handshake, value);
+    return encryption_config::mode_to_string(policy.handshake);
+  };
+
+  CPPUNIT_ASSERT_EQUAL(std::string("deny"), round_trip_handshake("deny"));
+  CPPUNIT_ASSERT_EQUAL(std::string("allow"), round_trip_handshake("allow"));
+  CPPUNIT_ASSERT_EQUAL(std::string("prefer"), round_trip_handshake("prefer"));
+  CPPUNIT_ASSERT_EQUAL(std::string("require"), round_trip_handshake("require"));
+
+  auto round_trip_stream = [](const std::string& value) {
+    encryption_config::Policy policy;
+    encryption_config::apply_mode_value(policy, &encryption_config::Policy::stream, value);
+    return encryption_config::mode_to_string(policy.stream);
+  };
+
+  CPPUNIT_ASSERT_EQUAL(std::string("deny"), round_trip_stream("deny"));
+  CPPUNIT_ASSERT_EQUAL(std::string("allow"), round_trip_stream("allow"));
+  CPPUNIT_ASSERT_EQUAL(std::string("prefer"), round_trip_stream("prefer"));
+  CPPUNIT_ASSERT_EQUAL(std::string("require"), round_trip_stream("require"));
+}

test/src/test_encryption_config.h

@@ -0,0 +1,12 @@
+#include "test/helpers/test_fixture.h"
+
+class TestEncryptionConfig : public test_fixture {
+  CPPUNIT_TEST_SUITE(TestEncryptionConfig);
+  CPPUNIT_TEST(test_default_policy);
+  CPPUNIT_TEST(test_granular_round_trip);
+  CPPUNIT_TEST_SUITE_END();
+
+public:
+  void test_default_policy();
+  void test_granular_round_trip();
+};