Enable independent Core and DSP owner updates

[dillonlille]

The directory-backed owner dashboard could not install the independently published Core and DSP releases. Add separate Core and DSP update pages backed by verified GitHub release discovery and a durable worker outside the replaceable Core service tree.

• Update Core snapshots Core state, swaps shared services, verifies API/database health and restores code and state on failure. DSP code remains independently selected.
• Update Dev targets the permanent test DSP. Rollout Update rechecks Dev health, stays pinned to its release and updates one DSP at a time, with pause/resume and interruption recovery. A newer release resets the Dev gate before rollout.
• DSP updates preserve individual settings, credentials, sessions and databases. New DSPs use the last completed fleet release. Idle DSPs can wake for an update; explicit owner stops remain protected.
• Owner commands require current authorization, CSRF and idempotency. Release acceptance checks repository, main commit, release-workflow provenance, version immutability, archive inventory and plugin packages.

Validation: 110 unit tests, 132 integration tests, three desktop/mobile browser checks, source checks, dashboard build, workflow lint and public source review pass locally. GitHub Core checks pass for b6b4cbab7462512570ed654203bf51755bcf0460 (run), including the browser workflow. The native Linux/systemd acceptance test installs Paycom in a synthetic DSP, switches releases and verifies private-state rollback. The real published Core/DSP 0.0.1 feeds were verified and staged without activation.

Deployment: this PR changes Core only. It does not publish or install a release. Core 0.0.1 predates the updater; the initial split deployment, permanent Dev selection and worker setup still require a separate installation rehearsal. Core lifecycle tests exercise real files/SQLite with injected service control; a full Core service swap must be rehearsed before live cutover. Setup, recovery and retention limits are documented in core/updates/README.md.