server roles, event loops, companion transports, storage and prefs.json

Server roles (slice 7)
- CommonCLI split into upstream's shape; region CLI moved into CommonCLI;
  ClientACL, RegionMap, TransportKeyStore and both server meshes in
  upstream shape over an Arduino compat shim (helpers/compat: Arduino.h,
  Stream/Print, Serial, SHA256, FILESYSTEM/File over Zephyr fs)
- room server processAck port; `get acl` prints as upstream
- room: default name Room-XXXX, display/input rotation, live radio UI refresh

Event loops (slice 7b)
- repeater and room server share server_main_common with a ServerRole
  descriptor; shared event bits in src/mesh_events.h
- room server deadline-driven (idle wakes 2.2/s -> 0.08/s); companion
  loop() runs on housekeeping (closes the lazy contact-flush gap)
- `get loop.wakes` in debug builds (CONFIG_ZEPHCORE_LOOP_WAKE_STATS)

Companion transports and WiFi (slice 8)
- upstream MultiSerialInterface: BLE, USB/UART and TCP are each a
  BaseSerialInterface, every connected transport gets every frame;
  CompanionSerial holds a lossless reply; shared frame_txq for BLE/TCP
- SerialCompanionTransport and LinuxTCPTransport replaced by
  TcpCompanionTransport; ZephyrBLE split (gatt layout, DFU)
- WiFi companion (upstream wifi.ssid/pwd/enabled CLI, TCP port 5000) on
  boards declaring `capabilities: wifi` in zephcore.yml: the PSRAM
  ESP32-S3 boards, plus Heltec V3 (140 contacts), Wireless Tracker (130)
  and both C6 boards (280); ESP32-S3 without PSRAM gets bounded WiFi
  buffers and a measured 72 KB heap; PSRAM boards' internal heap 72 KB
- TCP queues: own depth (ZEPHCORE_TCP_QUEUE_SIZE=8), RX waits instead
  of dropping
- RAM: companion ClientACL dropped; main/BT-TX/TCP stacks sized from
  measured peaks (-7 KB nRF companions, -9 KB ESP32 companions)
- ESP32 WiFi stopped working under ~200 frames/s unicast. Fixed by:
  patches/zephyr/0017 never block the WiFi task in the RX callback;
  patches/zephyr/0018 lock shared_multi_heap (heap corruption with the
  WiFi heap in PSRAM); patches/modules/hal_espressif/0001 backport of
  hal_espressif af97fb02df (PSRAM realloc)

Storage and prefs (slice 9)
- prefs are now prefs.json through upstream's ConfigSerializer (ported
  verbatim), with upstream's key names for shared fields and ZephCore's
  own under "zc"; on first boot the binary new_prefs / repeater prefs is
  migrated and kept, so a downgrade still boots with the old settings
- helpers/PrefsCodec: both legacy binary layouts (companion 272 B,
  server 311 B) as Zephyr-free codecs; sanitizeNodePrefs is the only
  validator
- fix: server prefs could be replaced by a truncated file when a write
  failed; identity, prefs and channel writes go through one checked
  atomic replace (ZephyrFsUtil)
- fix: a corrupt cad_auto byte turned adaptive CAD off instead of the
  default on
- fix: a deliberate 300 s GPS duty on a repeater was rewritten to 48 h
  on every boot (that migration now runs on legacy files only)
- one identity loader for all roles (IdentityFile); an unusable key
  file is always parked as .bad before regenerating
- server store no longer stamps repeater defaults on room server and
  observer; companion first-boot volume policy moved into the store
  (adoptVolume)
- ZephyrDataStore 1435 -> ~850 lines

zephcore/app/CompanionMesh.cpp

@@ -14,7 +14,9 @@
 #include <zephyr/sys/reboot.h>
 #include <ZephyrSensorManager.h>
 #include <adapters/sensors/SimpleLPP.h>
+#if IS_ENABLED(CONFIG_BT)
 #include <adapters/ble/ZephyrBLE.h>
+#endif
 #include <adapters/gps/ZephyrGPSManager.h>
 #include <helpers/time_sync.h>
 #include <adapters/clock/ZephyrRTCDiscover.h>
@@ -64,8 +66,7 @@ CompanionMesh::CompanionMesh(mesh::Radio &radio, mesh::MillisecondClock &ms, mes
 	ZephyrDataStore &store)
 	: BaseChatMesh(radio, ms, rng, rtc, mgr, tables), _store(&store)
 {
-	_push_cb = nullptr;
-	_write_cb = nullptr;
+	_serial = nullptr;
 	_batt_cb = nullptr;
 	_radio_reconfig_cb = nullptr;
 	_pin_change_cb = nullptr;
@@ -319,13 +320,16 @@ void CompanionMesh::flushDirtyChannels()
 	}
 }
 
+void CompanionMesh::startInterface(BaseSerialInterface &serial)
+{
+	_serial = &serial;
+	serial.enable();
+}
+
 bool CompanionMesh::writeFrame(const uint8_t *data, size_t len)
 {
 	LOG_DBG("RSP: 0x%02x len=%u", data[0], (unsigned)len);
-	if (_write_cb) {
-		return _write_cb(data, len) == len;
-	}
-	return false;
+	return _serial && _serial->writeFrame(data, len) == len;
 }
 
 void CompanionMesh::writeOKFrame()
@@ -350,14 +354,25 @@ void CompanionMesh::sendPacketSent(uint8_t result, uint32_t tag, uint32_t est_ti
 	writeFrame(rsp, sizeof(rsp));
 }
 
+/* [push_code][data...], only while an app is listening (pushes are lossy) */
 void CompanionMesh::sendPush(uint8_t code, const uint8_t *data, size_t len)
 {
-	LOG_DBG("sendPush: code=0x%02x len=%u _push_cb=%s", code, (unsigned)len, _push_cb ? "set" : "NULL");
-	if (_push_cb) {
-		_push_cb(code, data, len);
-	} else {
-		LOG_WRN("sendPush: _push_cb is NULL, push lost!");
+	if (!_serial || !_serial->isConnected()) {
+		return;
 	}
+
+	uint8_t frame[MAX_FRAME_SIZE];
+
+	if (1 + len > MAX_FRAME_SIZE) {
+		LOG_WRN("push 0x%02x: data too long %u", code, (unsigned)len);
+		len = MAX_FRAME_SIZE - 1;
+	}
+	frame[0] = code;
+	if (len > 0 && data != nullptr) {
+		memcpy(&frame[1], data, len);
+	}
+	LOG_DBG("sendPush: code=0x%02x len=%u", code, (unsigned)(1 + len));
+	writeFrame(frame, 1 + len);
 }
 
 size_t CompanionMesh::serializeContact(uint8_t *buf, const ContactInfo &c, uint8_t header)
@@ -2233,8 +2248,10 @@ bool CompanionMesh::handleCmdSetAdvertName(const uint8_t *data, size_t len)
 		memcpy(prefs.node_name, &data[1], nlen);
 		prefs.node_name[nlen] = '\0';
 		_store->savePrefs(prefs);
+#if IS_ENABLED(CONFIG_BT)
 		/* Push the new name to BLE so scanners see it without a reboot. */
 		zephcore_ble_update_name(prefs.node_name);
+#endif
 		/* v-contact name tracks the node name — update the app's copy. */
 		vcontactPushAdvert();
 	}
@@ -2523,7 +2540,9 @@ bool CompanionMesh::handleCmdSyncNextMessage(const uint8_t *data, size_t len)
 		/* Initial sync is done — safe to apply deferred
 		 * connection parameters now without disrupting
 		 * channel/contact/message throughput. */
+#if IS_ENABLED(CONFIG_BT)
 		zephcore_ble_conn_params_ready();
+#endif
 
 		/* Full initial sync (contacts + messages) complete: stop
 		 * suppressing v-contact notice prompts. Any notice queued during