feat(ci): baked CI image + runner config + self-check workflow (T14)

Stand up the foundation's own CI on its Forgejo runner. The committed scope here
is the self-contained half (toolchain + typecheck); the stack-state-dependent
pipelines (pulumi preview, backup-verify) need CI secrets + a state fetch and
land next.

- containers/ci-image/Dockerfile + VERSIONS IMAGE_CI: one baked image carrying
  exactly what preflight validates (pulumi/bun/node/docker/git/age/zstd/jq/vault/
  psql/mc). Built on the VM (like caddy-cloudflare) and used LOCALLY by the runner.
- runner.ts: give act_runner a config.yaml — container.network=foundation-net (so
  job containers reach foundation-forgejo:3000 for checkout + the data plane) and
  force_pull=false (use the local foundation-ci image, no registry). Self-heals on up.
- .forgejo/workflows/ci.yml: preflight (tools + versions vs VERSIONS pins) +
  typecheck (bun install + tsc --noEmit on bootstrap). Gates every push.
- run.sh / backup.sh / restore.sh / dr: take PULUMI_CONFIG_PASSPHRASE from env when
  set (CI secret), falling back to `pass` (operator) — so the scripts run pass-free
  in CI.

Reusable-workflows architecture (per the chosen direction) — the ecosystem CI
(semantic-release, docker/npm/bun builds, eslint/yamllint over the 999_testing.md
candidates) builds on this image + runner next phase.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

dr/restore-to-fresh-vm.sh

@@ -29,7 +29,7 @@ while [ $# -gt 0 ]; do case "$1" in
 [ -n "$TS" ]   || { echo "--ts <UTC-timestamp> required (a bundle in the offsite bucket)" >&2; exit 2; }
 
 export PULUMI_BACKEND_URL="file://${DIR}/state"
-export PULUMI_CONFIG_PASSPHRASE="$(pass olsitec-foundation/PULUMI_CONFIG_PASSPHRASE)"
+export PULUMI_CONFIG_PASSPHRASE="${PULUMI_CONFIG_PASSPHRASE:-$(pass olsitec-foundation/PULUMI_CONFIG_PASSPHRASE)}"
 cd "$DIR"; pulumi stack select foundation >/dev/null
 
 # Secrets from passphrase-encrypted config (the disaster-survivable set).