Add entrypoint script for configurable Reticulum networking in Docker

Replaces static CMD with an entrypoint that generates RNS config from
environment variables (RNS_TCP_HOST/PORT), enabling TCP transport for
environments without LAN auto-discovery (e.g. Docker on macOS).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

entrypoint.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+# Generate Reticulum config with optional TCP peer
+# Set RNS_TCP_HOST and RNS_TCP_PORT env vars to connect to a remote instance
+
+CONFIG_DIR="/data/.reticulum"
+CONFIG_FILE="$CONFIG_DIR/config"
+
+mkdir -p "$CONFIG_DIR"
+
+if [ ! -f "$CONFIG_FILE" ]; then
+  cat > "$CONFIG_FILE" <<EOF
+[reticulum]
+  enable_transport = False
+  share_instance = Yes
+
+[logging]
+  loglevel = 4
+
+[interfaces]
+  [[Default Interface]]
+    type = AutoInterface
+    enabled = Yes
+EOF
+
+  if [ -n "$RNS_TCP_HOST" ]; then
+    RNS_TCP_PORT="${RNS_TCP_PORT:-4242}"
+    cat >> "$CONFIG_FILE" <<EOF
+
+  [[TCP Link]]
+    type = TCPClientInterface
+    enabled = yes
+    target_host = $RNS_TCP_HOST
+    target_port = $RNS_TCP_PORT
+EOF
+  fi
+fi
+
+export RNS_CONFIG_DIR="$CONFIG_DIR"
+exec python app.py