fix(installer): force lowercase hostname in merge_config

Moves hostname normalization into merge_config() so it applies
regardless of source (CLI flag, env var, config file, prompt,
auto-detect). Logto normalizes hostnames internally — case mismatch
causes JWT issuer validation failure (401).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

installer/install.sh

@@ -494,6 +494,9 @@ merge_config() {
   : "${COMPOSE_PROJECT:=$DEFAULT_COMPOSE_PROJECT}"
   : "${DOCKER_SOCKET:=$DEFAULT_DOCKER_SOCKET}"
 
+  # Force lowercase hostname — Logto normalizes internally, case mismatch breaks JWT validation
+  PUBLIC_HOST=$(echo "$PUBLIC_HOST" | tr '[:upper:]' '[:lower:]')
+
   if [ -z "$NODE_TLS_REJECT" ]; then
     if [ "$TLS_MODE" = "custom" ]; then
       NODE_TLS_REJECT="1"