feat: add SolaX cloud lattice fragment publisher

[mgazza]

Summary

• add a pure, default-off SolaX Cloud Lattice fragment publisher
• model plants, real inverter hardware and provider-local synthetic battery references without touching the live SolaX API integration
• publish immutable REFERENCE-only topology and strong serial identity only for real hardware
• route discovery, liveness and removal changes through the common fragment invalidation / fresh-read recompile path

Safety

• not registered or invoked by live BatPred runtime code
• emits no capabilities, roles, runtime config or write authority
• synthetic batteries cannot emit hardware identity aliases or masquerade as independently controllable devices
• stale discovery/liveness versions are ignored and same-version divergence fails closed
• identity collisions fail before publication
• removal is a durable irreversible tombstone
• no solax.py imports, edits, registration or cloud/control side effects

Invalidation contract

Every accepted semantic change advances the provider generation and invalidates the common compiler. The compiler drains invalidations using fresh provider reads, so coalesced discovery/liveness/removal updates cannot compile an event payload that has already become stale.

Validation

• 99 focused and shared fragment/autoconfig/publication tests passed
• Python 3.9 and 3.14 focused validation passed
• black, ruff, cspell and diff checks passed
• independent review: no blocking findings
• GitNexus staged analysis: MEDIUM aggregate, 56 additive symbols, one internal set_liveness → read_state flow; live SolaX code remains untouched

Follow-up boundary

When a live mapper is introduced, it must additionally prove each synthetic battery source_serial belongs to a real inverter in the same plant before accepting provider data. This pure fragment is still safe without that mapping because synthetic nodes carry no strong identity, capability, role, config or authority.

Stack

• Base: feat(lattice): publish GE Cloud topology fragments #4332
• Tracking: Predictive-Cloud-Ltd/predbat-saas-infra#466
• Fragment programme: Predictive-Cloud-Ltd/predbat-saas-infra#561