feat!: remove the old API, ports 8081 and 8080 (step 4a)

Step 4a of docs/SECURITY_PLAN.md. Port 80 keeps the eleven HTTP routes of
ADR 0006 and the socket at /ws; everything else moved to protocol 2.

- Port 8081 (ApiRoutes) and the socket on 8080 (SocketEmitter) are gone.
  Protocol 2 owns its frame buffer and loop-task check.
- Port 80 drops every route the old web UI called: reads, edits,
  settings, scans, reboot, /shades.cfg, /discovery. HttpRoutes.cpp holds
  what stays.
- ModelSnapshot, SnapshotSlots and the read documents are gone. The item
  snapshot types stay, as ItemSnapshot, for events, MQTT and the command
  replies.
- Model edits reply only to their protocol 2 op: requestResult goes.
- The settings' toJSON writers, used only by the settings routes, go.
- The _espsomfy_rts._tcp mDNS record moves to port 80, with path=/ws.
- The memory event reports the loop-rate window it closes.
- A deleted room no longer re-publishes its retained MQTT topics.
- e2e: the heap check reads the sync's status; the sync is checked on
  its own instead of against /controller.
- README gets an API and ports section.

BREAKING CHANGE: ports 8081 and 8080 and the old HTTP routes are gone.
Home Assistant needs integration 3.0.0 or newer.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/test_itemsnapshot/test_itemsnapshot.cpp

@@ -0,0 +1,79 @@
+#include <unity.h>
+#include <string.h>
+#include <string>
+#include "ItemSnapshot.h"
+
+static shade_snapshot_t shade(uint8_t id, const char *name) {
+  shade_snapshot_t s{};
+  s.shadeId = id;
+  s.roomId = 2;
+  strcpy(s.name, name);
+  s.remoteAddress = 1000 + id;
+  s.paired = true;
+  s.shadeType = 1;
+  s.bitLength = 56;
+  s.repeats = 1;
+  return s;
+}
+static group_snapshot_t group(uint8_t id, const char *name) {
+  group_snapshot_t g{};
+  g.groupId = id;
+  strcpy(g.name, name);
+  g.remoteAddress = 2000 + id;
+  g.lastRollingCode = 5;
+  g.bitLength = 80;
+  g.repeats = 2;
+  return g;
+}
+static std::string shadeRefJson(const shade_snapshot_t &s) {
+  static char buf[1024];
+  BufferedJsonFormatter fmt;
+  fmt.setBuffer(buf, sizeof(buf));
+  fmt.beginObject();
+  writeShadeRef(fmt, s);
+  fmt.endObject();
+  return std::string(buf, fmt.length());
+}
+static std::string groupRefJson(const group_snapshot_t &g) {
+  static char buf[1024];
+  BufferedJsonFormatter fmt;
+  fmt.setBuffer(buf, sizeof(buf));
+  fmt.beginObject();
+  writeGroupRef(fmt, g);
+  fmt.endObject();
+  return std::string(buf, fmt.length());
+}
+
+void setUp() {}
+void tearDown() {}
+
+/*********************************************************************
+ * The command replies, as the routes have always written them
+ ********************************************************************/
+static void test_a_shade_ref() {
+  TEST_ASSERT_EQUAL_STRING(
+    "{\"shadeId\":1,\"roomId\":2,\"name\":\"Kitchen\",\"remoteAddress\":1001,\"paired\":true,\"shadeType\":1,"
+    "\"flipCommands\":false,\"flipPosition\":false,\"bitLength\":56,\"proto\":0,\"flags\":0,\"sunSensor\":false,"
+    "\"hasLight\":false,\"repeats\":1}",
+    shadeRefJson(shade(1, "Kitchen")).c_str());
+}
+static void test_a_group_ref() {
+  TEST_ASSERT_EQUAL_STRING(
+    "{\"groupId\":6,\"roomId\":0,\"name\":\"All\",\"remoteAddress\":2006,\"lastRollingCode\":5,\"bitLength\":80,"
+    "\"proto\":0,\"sunSensor\":false,\"flipCommands\":false,\"flags\":0,\"repeats\":2,\"sortOrder\":0}",
+    groupRefJson(group(6, "All")).c_str());
+}
+static void test_names_are_escaped() {
+  const std::string json = shadeRefJson(shade(1, "A \"big\" one"));
+  TEST_ASSERT_NOT_EQUAL(std::string::npos, json.find("\"name\":\"A \\\"big\\\" one\""));
+}
+
+int main(int argc, char **argv) {
+  (void)argc;
+  (void)argv;
+  UNITY_BEGIN();
+  RUN_TEST(test_a_shade_ref);
+  RUN_TEST(test_a_group_ref);
+  RUN_TEST(test_names_are_escaped);
+  return UNITY_END();
+}