fix: align the developer template and harness with OpenClaw 2026.8

[paleo]

• Upgraded the test harness to OpenClaw 2026.8.2 (core, plugin pins, lockfiles).
• Deployment template: the heartbeat checklist moves from HEARTBEAT.md to the heartbeat-main cron job's scratch, shipped as heartbeat-scratch.md; the seed drops the custom heartbeat prompt and pins directPolicy per surface.
• Deployment template: the seed disables the memory plugin, the pre-compaction memory flush, cross-conversation recall, the autonomous skill workshop and the startup update check.
• Deployment template: the seed records plugin capability consent, and its secrets audit tolerates the informational OAuth-login finding.
• Deployment template runbooks: backup before a core bump (now including OpenClaw's SQLite archive), openclaw update repair as the migration step, chmod go-w before gateway install, cron list and scratch checks in the smoke test, new gotchas (background model runs, slot plugins, systemd path permissions, sudo -i line continuations, pinned-install plugin drift).
• Harness config carries the same opt-outs as the seed.
• Upgrade procedure: doctor runs on both shipped workspaces, compares the template's workspace files with the runtime's bootstrap list, diffs config defaults between tags, and inspects a running gateway's jobs and plugins.
• Context-engineering doc: heartbeat scratch and default-on background runs.