v1.0.5: Heltec V3 support, heap stability fix, TCP reconnection improvements

- Add Heltec WiFi LoRa 32 V3 board support (8MB flash, 8MB PSRAM)
  - New heltec_V3_boundary build environment in platformio.ini
  - Board auto-detection in flash.py (8MB=V3, 16MB=V4)
  - V3 board definition in Boards.h
- Fix heap exhaustion causing watchdog reboots every ~70 min
  - Lower boundary_mentioned_addresses cap from 512 to 200
  - Heap now stable at ~38KB free (was draining to 0)
- TCP reconnection improvements in TcpInterface.h
  - SO_LINGER(0) for clean socket teardown
  - 10-minute read timeout prevents zombie connections
  - Defensive client cleanup on accept
- Add heap telemetry instrumentation (HEAP-TEL) for monitoring
- Add level guards on TRACE/DEBUG macros in Log.h
- Update README for dual V3/V4 board support

Boards.h

@@ -349,7 +349,11 @@
       #define HAS_DISPLAY true
       #define HAS_WIFI true
       #define HAS_BLUETOOTH false
-      #define HAS_BLE true
+      #ifdef BOUNDARY_MODE
+        #define HAS_BLE false
+      #else
+        #define HAS_BLE true
+      #endif
       #define HAS_PMU true
       #define HAS_CONSOLE true
       #define HAS_EEPROM true