AUD-56: deploy prep - token script, container user fix, runbook

- Add scripts/provision-hub-tokens.sh. It adds the five HUB_TOKEN_* keys to
  ~/.config/environment.d/10-secrets.conf. It is idempotent, keeps mode 600,
  leaves a mode-600 backup, and never prints a value. It uses openssl when
  present and /dev/urandom otherwise (this host has no openssl).
- docker-compose.yml: run the container as the host user. The image's
  distroless nonroot user cannot read the 0600 secrets file. With nonroot the
  Hub read no tokens and every /ask returned 401.
- Document the deploy steps, the finding, and the dry-run evidence in
  docs/outline/04-agent-runbook.md, docs/outline/02-config-and-env.md, README.md.

Dry run on port 18788 with a scratch secrets file: /health ok with
omniroute ok, control action refused, bad token 401. The host secrets file and
the running hub container were not touched.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

docs/outline/02-config-and-env.md

@@ -23,6 +23,14 @@ Relevant keys:
 | `HUB_TOKEN_CONSOLE` | Hub token for the console portal. |
 | `HUB_TOKEN_ADMIN` | Hub token for the admin app. The only trusted door. |
 
+Add the five Hub tokens with `scripts/provision-hub-tokens.sh`. It is
+idempotent, keeps mode 600, and never prints a value. A new token needs Sam's OK
+(`AGENTS.md` "ask first: credentials").
+
+The container runs as the host user (`HUB_UID`/`HUB_GID`, default `1000:100`),
+not the image's `nonroot` user, because the secrets file has mode 0600 and the
+`nonroot` user cannot read it. See `docs/outline/04-agent-runbook.md`.
+
 ## Hub Environment Keys
 
 The Hub reads these keys from the environment, then from the secrets file. The