docs(skill): use mureo_state_* MCP tools for STATE.json mutations on Code (#341)

[hyoshi]

Summary

skills/_mureo-shared/SKILL.md's "Tool Selection" table told Claude Code
agents to upsert campaign snapshots / append action_log entries to STATE.json
via the raw Edit tool. But the v2 schema the dashboard reads is non-trivial —
a platforms[<platform>] section with a required account_id — and a
platform/campaign missing it is silently dropped, so the workspace renders
empty / "not yet bootstrapped" even after campaigns were written
(mureo/context/state.py:386, mureo/_data/web/dashboard.js:2155). The
mureo_state_* MCP tools encode that schema atomically and are available on
Code too. Separately, mureo_state_upsert_campaign (and the metrics/report
setters) stamp the top-level last_synced_at that drives the dashboard's
"Synced N ago" freshness — and that field was entirely absent from the
SKILL.md STATE.json Schema docs.

Changes (mirrored to both skills/ and mureo/_data/skills/)

• _mureo-shared/SKILL.md
  • Table "Append action_log entry" / "Upsert campaign snapshot" Code column:
    Edit → the mureo_state_* MCP tool (matches the issue's suggested diff).
  • Note: STATE.json mutations prefer the MCP tool on every host; direct
    Write on Code is reserved for the bulk-snapshot flows
    (sync-state / daily-check), where the agent must replicate the full
    schema incl. a fresh last_synced_at.
  • Added last_synced_at as a required top-level field (bullet + JSON
    example) — the missing piece behind the reported failure.
• daily-check/SKILL.md step 11: a last_synced_at reminder for the Code
  Write path (sync-state already had step 9).

Verification

• Code-reviewed (code-reviewer agent). It caught two prose inaccuracies in an
  earlier draft, now corrected and re-verified against the implementation:
  • platforms / account_id incompleteness — not last_synced_at — is
    what renders a workspace empty/inactive (dashboard.js:2155 gates on
    platforms.length === 0); last_synced_at only drives the freshness label.
  • mureo_state_action_log_append does not re-stamp last_synced_at
    (state.py:463 preserves it); only the campaign/metrics/report writers do.
• Mirror parity test tests/test_plugin_manifests.py passes (skills/ ↔
  mureo/_data/skills/ byte-identical); skill suite green (247 passed).
• Docs-only change.

Closes #341

https://claude.ai/code/session_011rAu94b1o1xWYZhARk1VmL