fix: bug: code fixes to docker/agents/ don't take effect — agent image is never rebuilt (#887)

Add `pull_policy: build` to every agent service emitted by the generator
that shares `docker/agents/Dockerfile` as its build context. Without it,
`docker compose up -d --force-recreate agents-<name>` reuses the cached
`disinto/agents:latest` image and silently keeps running stale
`docker/agents/entrypoint.sh` code even after the repo is updated. This
masked PR #864 (and likely earlier merges) — the fix landed on disk but
never reached the container.

#853 already paired `build:` with `image:` on hired-agent stanzas, which
was enough for first-time ups but not for re-ups. `pull_policy: build`
tells Compose to rebuild the image on every up; BuildKit's layer cache
makes the no-change case near-instant, and the change case picks up the
new source automatically. This covers:

- TOML-driven `agents-<name>` hired via `disinto hire-an-agent` — primary
  target of the issue.
- Legacy `agents-llama` and `agents-llama-all` stanzas — same Dockerfile,
  same staleness problem.

`bin/disinto up` already passed `--build`, so operators on the supported
UX path were already covered; this closes the gap for the direct
`docker compose` path the issue explicitly names in its acceptance.

Regression test added to `tests/lib-generators.bats` to pin the directive
alongside the existing #853 build/image invariants.

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

lib/generators.sh

@@ -123,6 +123,11 @@ _generate_local_model_services() {
       context: .
       dockerfile: docker/agents/Dockerfile
     image: disinto/agents:\${DISINTO_IMAGE_TAG:-latest}
+    # Rebuild on every up (#887): without this, \`docker compose up -d --force-recreate\`
+    # reuses the cached image and silently keeps running stale docker/agents/ code
+    # even after the repo is updated. \`pull_policy: build\` makes Compose rebuild
+    # the image on every up; BuildKit layer cache makes unchanged rebuilds fast.
+    pull_policy: build
     container_name: disinto-agents-${service_name}
     restart: unless-stopped
     security_opt:
@@ -443,6 +448,9 @@ COMPOSEEOF
     build:
       context: .
       dockerfile: docker/agents/Dockerfile
+    # Rebuild on every up (#887): makes docker/agents/ source changes reach this
+    # container without a manual \`docker compose build\`. Cache-fast when clean.
+    pull_policy: build
     container_name: disinto-agents-llama
     restart: unless-stopped
     security_opt:
@@ -493,6 +501,9 @@ COMPOSEEOF
     build:
       context: .
       dockerfile: docker/agents/Dockerfile
+    # Rebuild on every up (#887): makes docker/agents/ source changes reach this
+    # container without a manual \`docker compose build\`. Cache-fast when clean.
+    pull_policy: build
     container_name: disinto-agents-llama-all
     restart: unless-stopped
     profiles: ["agents-llama-all"]