fix: scope circuit device ids to the panel that owns them

[cayossarian]

The collision

stable_circuit_uuid derived a circuit's Homie device id from the YAML circuit id alone. Those ids are shared vocabulary across the shipped configs — default_MAIN_32.yaml and default_MAIN_40.yaml both define a solar_inverter and an oven. A real panel has its own broker, so it cannot collide; two simulated panels in one add-on share one, and the two solar_inverters then claim the same device id and the same ebus/5/<uuid>/... topics.

Both panels write every tick, so a consumer reads each circuit's meters as the two unrelated loads alternating. Observed on ha-test with sim-32t-001 and sim-40t-001: 16 energy counters flipping between the two panels' values every tick (space 12 exported-energy 53.18 → 37.44 → 53.27 → 37.52), with Home Assistant's dip compensation firing continuously.

The change

stable_circuit_uuid(panel_id, circuit_id) hashes <panel-serial>/<circuit-id>, scoping a circuit the way every other id in instance_ids is already scoped to its proxier. The namespace is unchanged. The separator is / and not - because a panel serial may itself contain -, and any separator the serial can contain admits two different (panel, circuit) pairs hashing the same name.

Every caller now threads the panel serial from panel_config.serial_number — the one key, never a second one alongside it. _feeds_for_device_type reads it from the config it is already walking rather than taking it as a parameter, so a feed id cannot be built from a serial that does not own those circuits.

Cross-repo contract

The flat simulator publishes the same circuit ids for the same config, and the firmware-upgrade rehearsal stops one and starts the other on a single panel — a circuit whose id changed at the swap strands its Home Assistant history. The identical change lands in SpanPanel/simulator#50.

tests/test_instance_ids_contract.py pins the derivation as values rather than as a formula:

stable_circuit_uuid("sim-40t-001", "solar_inverter") == "be87c32bda4f5cd9abbf6d3995ae28c0"
stable_circuit_uuid("sim-40t-002", "solar_inverter") == "946438eed82a57f3a1d7cbeea37bbb29"

The simulator's suite asserts the same two, so a change made on one side alone fails CI on both. Two rather than one because a single value cannot distinguish the panel scoping from any other change that happens to agree on one input; the pair differs only in the serial, which pins the serial as an input rather than as a constant folded into the namespace. A third test states the bug itself: two panels sharing a circuit id must not share a device id.

Fixtures

golden_wire.json was recaptured with scripts/capture-wire.py. golden_tree.json had its circuit ids rewritten in place, and golden_report.json was regenerated from it per DEVELOPER.md — the regenerated report is the old one's observations unchanged as a multiset, reordered only because the report sorts by device id.

Upgrade note

Released as 2.5.3. A simulated panel already added to Home Assistant has to be removed and re-added: its circuits get new device ids, so its circuit entities get new unique ids.

Full suite (394 tests) and pre-commit run --all-files are green.