chore(scripts): add update.sh, hook it into agent/deploy workflow

One script to bring the running stack in sync after any change: git pull,
validate compose config, rebuild the litellm-pgvector local build, re-pull
images, recreate what changed. Documented in README's quickstart, and
CLAUDE.md now tells agents to run it after touching compose/config/scripts
rather than just describing a change as done.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

@@ -24,6 +24,8 @@ docker compose up -d
 
 Pointing Claude Code CLI, Kimi CLI, or OpenCode CLI at the local endpoint: see [`docs/coding-cli-setup.md`](docs/coding-cli-setup.md).
 
+**Applying updates**: after pulling changes (or editing `docker-compose.yml`/`litellm-config.yaml`/`.env` yourself), run `./scripts/update.sh` — pulls, validates the compose config, rebuilds/re-pulls images, and recreates whatever changed. Safe to run any time.
+
 **Known risk**: Qwen3.8-27B's tool-calling reliability against llama.cpp's Anthropic shim is not yet verified (open upstream parser bugs against its model lineage) — see `docs/research/qwen3.8-27b-tool-calling.md`.
 
 ## AI proxy (LiteLLM)