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>

src/Utils.h

@@ -57,16 +57,16 @@ struct rebootDelay_t {
   else if(str[0] == 'f' || str[0] == 'F' || str[0] == '0') return false;
   return def;
 }
-// Whether a wifiStrength broadcast is worth sending: always on a channel change,
+// Whether a wifi broadcast is worth sending: always on a channel change,
 // otherwise only for an RSSI change of at least minDelta dBm.
 bool rssiNeedsEmit(int rssi, int lastRssi, int channel, int lastChannel, int minDelta);
-// What the last wifiStrength broadcast told every client.  Only broadcasts
-// move it: an emit to one new client tells the others nothing.
+// What the last wifi broadcast told every client.  A client that connects gets
+// the signal in its sync, which tells the others nothing, so it isn't moved.
 struct RssiBroadcast {
   int rssi = 0;
   int channel = 0;
   bool due(int rssi, int channel, int minDelta) const;
-  void sent(bool broadcast, int rssi, int channel);
+  void sent(int rssi, int channel);
 };
 // Whether an AP a scan found for our SSID is worth connecting to.  While
 // connected it has to be at least minGain dBm stronger than the current AP so
@@ -74,7 +74,7 @@ struct RssiBroadcast {
 bool worthRoaming(bool connected, int currentRssi, int apRssi, int minGain);
 // Whether the calling task may send socket events.  They are all formatted
 // into one shared buffer, so only loop()'s task may.  owner is that task, or
-// null before SocketEmitter::begin() has recorded it (setup() runs there too).
+// null before ProtoSocket::begin() has recorded it (setup() runs there too).
 bool emitAllowed(const void *current, const void *owner);
 // A short name for a wifi_auth_mode_t value, for the logs.  The values up to
 // WAPI are the same in ESP-IDF 4.4 and 5.x.
@@ -91,10 +91,9 @@ void releaseAssetName(char *buf, size_t size, const char *kind, const char *chip
 // depth is how many the dump claims are valid.
 void formatBacktrace(char *buf, size_t size, const uint32_t *bt, size_t maxFrames, uint32_t depth);
 // How well loop() keeps up: the passes it made per second and its longest
-// pass, over the window since the last memStatus broadcast.  Only the loop
+// pass, over the window since the last memory broadcast.  Only the loop
 // task calls record(), rate(), maxUs() and publish().  publish() closes the
-// window and keeps its figures where another task (the /discovery response)
-// can read them without seeing a half reset window.
+// window and keeps its figures for the memory event and a client's sync.
 class LoopStats {
   uint32_t _passes = 0;
   uint32_t _maxUs = 0;