fix(mock-synapse): synapse→hass bridge so TS-written entities surface on the hass mock bus

[zoe-codez]

Draft — part of a cross-repo HA testing-suite effort.

The seed bug this fixes

synapse-created entities written from TS did not surface on the hass mock event bus, so cross-module hass listeners never fired in tests.

What this adds (synapse/src/mock/)

• synapse→hass bridge: on synapse storage.set, routes the new value through the hass socket path (auto-registers the entity, emits one state_changed) so e.g. a synapse switch toggle fires hass-bus listeners.
• F5 timing: registers each entity into the mock seed store at synapse storage.add; defers pre-connect writes until the socket reports connected.
• F6 loop guard: bridge-originated emits carry an origin tag; synapse's reactive event.on(unique_id) ignores tagged events — breaks the storage.set → bridge → socket → event.on cycle.
• Fake-timer fix: bridge onBootstrap setImmediate → microtask (Promise.resolve()); setImmediate was captured by vi.useFakeTimers() and hung forever (the real root cause of the harness hangs).
• Adds ./mock package export; portal: local-hass linkage with a single @digital-alchemy/core@26.5.30 pin; backbone bug-proof spec.

Gates

• vitest: 148 pass / 75 skip (pg/mysql live-DB integration specs gated on DB_PG/DB_MYSQL).

Note

Depends on the hass mock_assistant backbone PR (Digital-Alchemy-TS/hass#253) via the local portal pin.