fix(update): load .env before invoking python updaters

`update.yml` jobs (Docker image versions, repository refs) shelled
straight into `python3 -m cli.contributing.update.{docker,repository}`
without sourcing the project dotenv. After eb4bcd23a removed the
`.get(..., default)` fallback in resolve_max_fetch_workers(),
KeyError: 'INFINITO_WORKER_FETCH' surfaced on every run.

Both wrapper scripts now `make dotenv` (idempotent) and `set -a; . .env;
set +a` before exec'ing the updater, restoring the SPOT env chain on
CI runners that don't go through compose.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/github/update/image_versions.sh

@@ -5,4 +5,8 @@ SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
 REPO_ROOT="$(cd -- "${SCRIPT_DIR}/../../.." && pwd)"
 
 cd "${REPO_ROOT}"
+make dotenv >/dev/null
+set -a
+. .env
+set +a
 python3 -m cli.contributing.update.docker "$@"

scripts/github/update/repository_refs.sh

@@ -5,4 +5,8 @@ SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
 REPO_ROOT="$(cd -- "${SCRIPT_DIR}/../../.." && pwd)"
 
 cd "${REPO_ROOT}"
+make dotenv >/dev/null
+set -a
+. .env
+set +a
 python3 -m cli.contributing.update.repository "$@"