infra/dev: env_value defaults match compose, die helper, shared Gradle lock check; drop unused RCLONE_REMOTE and M2a leftovers; fix stale Pi compose path

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

infra/dev/lib.sh

@@ -8,9 +8,13 @@ repo_root="$(cd "$dev_dir/../.." && pwd)"
 # infra/dev/.env (git-ignored) when it exists, otherwise the committed example.
 if [[ -f "$dev_dir/.env" ]]; then env_file="$dev_dir/.env"; else env_file="$dev_dir/.env.example"; fi
 
-# Value of KEY in the env file (empty when unset or blank).
+die() { printf '%s: %s\n' "$(basename "$0")" "$*" >&2; exit 1; }
+
+# Value of KEY in the env file; DEFAULT (the compose.yaml default, optional) when unset or blank.
 env_value() {
-  sed -n "s/^$1=//p" "$env_file" | tail -n 1
+  local v
+  v="$(sed -n "s/^$1=//p" "$env_file" | tail -n 1)"
+  printf '%s\n' "${v:-${2:-}}"
 }
 
 compose() {
@@ -31,9 +35,3 @@ lan_address() {
   iface="$(route -n get default 2>/dev/null | awk '/interface:/ {print $2}')"
   [[ -n "$iface" ]] && ipconfig getifaddr "$iface" 2>/dev/null
 }
-
-dev_port() {
-  local p
-  p="$(env_value KVITT_DEV_PORT)"
-  printf '%s\n' "${p:-8080}"
-}