feat(data): value-partitioned archetypes (shared components)

[krisnye]

Description

Adds value-partitioned archetypes (the "shared components" pattern) to the ECS. A component declared partition: true stores every distinct runtime value in its own archetype, whose partition column is a zero-per-row ConstTypedBuffer — so entities sharing a value are contiguous in memory (a storage-level coarse spatial broad phase).

Public surface

• partition: true schema marker (primitive components).
• ensureArchetype(keys, values?) — discriminated return: a Router (write-only) when the key set includes a partition component without a value; a concrete Archetype when a value is supplied or no partition key is present.
• Router — routes each insert by the row's partition value to the concrete child (created on first use).
• queryArchetypes(include, { where }) — partition-value filter, decided at archetype granularity (O(archetypes), no row scan).
• store.archetypes.<Name> and the transaction context t discriminate partitioned vs concrete per declared archetype.
• update migrates an entity between value-children when its partition value changes.

Internals

• Single resolveArchetype(keys, partitionValues?) primitive backs ensureArchetype, routing, migration, and restore.
• Index maintenance is wired via in-place insert decoration at archetype creation (onArchetypeCreated hook) — no Proxy, no forwarding wrapper. This also removes the pre-existing Proxy that wrapped concrete archetypes.
• Partition detection reads the live schema, so dynamically extending a store/database with partition components works.
• toData/fromData round-trips partition children (values + rows).

Type-perf

Flat, sub-quadratic scaling preserved — no TS7056 cliff (verified via scripts/typeperf). ~4% flat instantiation overhead when unused, from carrying PK through the composition types.

Also

Removes the unused, orphaned observeDependentValue helper (no internal, cross-package, or firefly-platform consumers) — which also removes a runtime Proxy.

Tests

Red/green compile-time type tests (positive + negative @ts-expect-error) at the isolated-helper, store, and transaction-context levels, plus runtime tests at the core, store, and database/transaction layers — including dynamic extend, N-distinct-values → N-archetypes with const columns, unique-index enforcement across value-children, and migration.

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