fix: bootstrap file permission denied, use PNG favicon

- Change chmod 600 to 644 on bootstrap JSON (cameleer user needs read)
- Use PNG favicon instead of SVG (currentColor invisible in browser tab)

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

docker/logto-bootstrap.sh

@@ -541,7 +541,7 @@ cat > "$BOOTSTRAP_FILE" <<EOF
   "oidcAudience": "$API_RESOURCE_INDICATOR"
 }
 EOF
-chmod 600 "$BOOTSTRAP_FILE"
+chmod 644 "$BOOTSTRAP_FILE"
 
 log ""
 log "=== Bootstrap complete! ==="