Fix TCP receive: path table update + interface naming + 10Mbps bitrate

- Fix path table insert bug: C++ map::insert() silently fails when key
  exists (unlike Python dict[key]=value). Changed to erase()+insert() so
  updated paths (e.g. local TCP replacing stale LoRa) actually take effect.
- Add name parameter to TcpInterface constructor to give each instance a
  unique identity hash, fixing map collision between backbone and local
  TCP server interfaces.
- Set TCP interface bitrate to 10 Mbps (was 500 bps) so Transport
  correctly prefers TCP paths over LoRa when both exist.
- Add PRG button hold >5s white screen indicator for config portal.
- Boundary mode cull_path_table: evict backbone paths first, preserving
  local paths needed for inbound routing.

Input.h

@@ -31,6 +31,7 @@
   
   int button_events = EVENT_CLICKS;
   int button_state = RELEASED;
+  bool display_lock_white = false;
   int debounce_state = button_state;
   unsigned long button_debounce_last = 0;
   unsigned long button_debounce_delay = 25;
@@ -82,6 +83,24 @@
       }
     }
 
+    // ── Live hold indicator: turn display white when held >5s ──
+    #ifdef BOUNDARY_MODE
+    {
+      if (button_state == PRESSED && button_down_last > 0) {
+        unsigned long held = millis() - button_down_last;
+        if (held > 5000 && !display_lock_white) {
+          display_lock_white = true;
+          #if HAS_DISPLAY
+          if (disp_ready) {
+            display.fillScreen(SSD1306_WHITE);
+            display.display();
+          }
+          #endif
+        }
+      }
+    }
+    #endif
+
   }
 
   bool button_pressed() {