Add Docker container restart/rebuild guidance to musehub's .muse/agent.md

Background

During the MWP-9 spot-check investigation (musehub#113), significant time was lost because musehub_worker (the background job container) was silently running a Docker image dated over a month old, while musehub (the API container) had been restarted recently. Nothing in the agent-facing docs distinguished the two containers — only musehub's restart was a documented habit. This produced misleading investigation results for a long stretch before the staleness was caught.

What was done

Added a rewritten "Localhost Containers" section to musehub/.muse/agent.md — the source file muse agent-config sync reads to regenerate CLAUDE.md / AGENTS.md / .cursorrules / .windsurfrules. Covers:

• Both musehub and musehub_worker must be restarted together after any code change — never just one.
• A concrete freshness-verification recipe (container uptime, image build timestamp, and specific log lines to grep for) to run before trusting any local test result, not after debugging goes sideways.
• When a plain docker restart is enough (bind-mounted .py edits) vs. when a full docker compose build is required (Dockerfile, dependency, or compose-file changes).
• Two distinct schema-migration failure modes surfaced in the same session (DB behind existing migrations vs. an ORM model with no migration ever generated for it) and the correct recipe for each.

Applied and verified in this session via muse agent-config sync --force and muse agent-config status (both report in sync).

Deliverables

• [x] Rewrite musehub/.muse/agent.md's "Localhost Container" section (done, this session).
• [x] Regenerate adapters via muse agent-config sync --force (done, confirmed in sync).
• [ ] Confirm this content actually reaches other machines/checkouts the way muse agent-config sync is expected to distribute it — flagged as a follow-up check, not resolved in this ticket, since the goal here was capturing the missing verbiage, not auditing the distribution mechanism itself.

Out of scope

• Auditing whether .muse/agent.md is tracked/pushed by muse itself — noted as an open follow-up above, not investigated further here.