ValueSourceStore.create_source used to be a ~260-line if/elif chain
over 14 source_type strings; update_source did the same dance again
with 14 isinstance branches (audit finding C7 store-side). Each
branch duplicated the common-fields scaffold and the per-type
defaulting + validation logic.
Lift each per-type create / update body into a free function in a
new ``storage.value_source_factories`` module:
* ``CREATE_BUILDERS[source_type]`` — owns defaulting + per-type
validation (HA needs ha_source_id + entity_id; gradient_map
needs value_source_id; system_metrics validates against
VALID_SYSTEM_METRICS; http rejects interval_s < 1; the two
adaptive_* sub-modes route to the same AdaptiveValueSource
class with different source_type discriminators).
* ``UPDATE_APPLIERS[source_type]`` — mirrors the above on the
update side; ``resolve_ref`` is applied to cross-entity
references so empty-string clears keep working.
* ``build_source(...)`` / ``apply_update(source, **kwargs)`` are
the public entry points the store calls.
* ``_assert_factory_coverage()`` runs at module import and
requires BOTH registries to match storage's _VALUE_SOURCE_MAP
exactly.
The store's ``create_source`` shrinks from ~260 lines to ~25;
``update_source`` from ~200 lines to ~40.
Tests: 14 new tests cover registry coverage in both directions
plus drift assertions, representative builder paths (static /
adaptive_time / adaptive_scene / ha_entity / http / unknown),
the AdaptiveValueSource dual-source-type discriminator, and
several applier paths including ``**_`` swallowing unknown kwargs
and HTTP zero-interval rejection. 47 existing value-source store
tests stay green; 769 storage / core / api tests in aggregate.
Ruff clean.
alexei.dolgolyov
3b8f00e3f9