Reshape shared/commonMain domain model

Replace the 11 hand-rolled model files with 7 grouped by concern. Typed
ID value classes kill bare-string FKs. Canonical 3-value MeasurementUnit
enum kills the runtime unitMismatch class — Polish vocabulary lives in
Quantity.displayHint as render-only metadata. MealExtras (5 maps) collapses
into IngredientCustomization + PlanCustomization. IngredientCategory and
MealSlot become household-scoped entities with LocalizedString names so
they're customizable without an app release. Display names land as
LocalizedString from day one; no Polish strings in identifiers or wire
codes. Recipe drops allowedSlots — slot affinity is a UI-layer match on
Recipe.tags vs MealSlot.name. Skip is absence, not a sealed sibling.

Plan: ~/.claude/plans/i-have-generated-some-inherited-conway.md.

Covered by SerializationRoundTripTest: 12 assertions across typed-ID
inlining, MeasurementUnit wire format, LocalizedString JSON shape, full
PlanEntry round-trip with every customization kind, SyncMeta tombstone
omission, and Catalog defaults handling. All targets compile and pass:
JVM, Android (debug + release), iOS Simulator Arm64.

shared/build.gradle.kts

@@ -23,11 +23,15 @@ kotlin {
     sourceSets {
         commonMain.dependencies {
             // Phase 2: DTOs land here (MeResponse/User per D-27). kotlinx.serialization
-            // is the only allowed runtime dependency in shared/commonMain — D-19 / INFRA-06
-            // forbids Ktor, Compose, SQLDelight, Koin, Kermit. `api(...)` so consumers
-            // (composeApp, server) inherit the @Serializable runtime without each
-            // re-declaring it.
+            // and kotlinx.datetime are the only allowed runtime dependencies in
+            // shared/commonMain — D-19 / INFRA-06 forbids Ktor, Compose, SQLDelight,
+            // Koin, Kermit. `api(...)` so consumers (composeApp, server) inherit the
+            // @Serializable runtime + datetime types without each re-declaring them.
             api(libs.kotlinx.serializationJson)
+            // Domain types need Instant (SyncMeta.updatedAt/createdAt/deletedAt) and
+            // LocalDate (PlanEntry.date). kotlinx.datetime is the project's locked
+            // datetime lib per CLAUDE.md; pure types, no platform deps.
+            api(libs.kotlinx.datetime)
         }
 
         commonTest.dependencies {