Wire metadata resolver into cache provider

Define ActivityTypeWithMetadata as a freezed data class with all fields from ActivityType plus the resolved metadata accessors as computed getters or pre-resolved fields. Two valid approaches: (A) eager resolution — resolve all metadata during cache.build() and store ActivityTypeWithMetadata directly; (B) lazy wrapper — store ActivityType + resolver reference and resolve on first accessor call with memoisation. Approach A is preferred for simplicity and predictability. In the cache provider's build() method, call: state = await repository.fetchActiveByOrganisation(orgId) then map each type through resolver.resolve(type).

Wrap the resolver call in a try/catch per item to implement per-item error isolation. Define the ActivityTypeWithMetadata model in a shared domain layer so all three downstream consumers (wizard, expense check, Bufdir) can import it without circular dependencies.

Unit tests using flutter_test and mocktail. Test cases: (1) ActivityTypeCacheProvider returns List after population; (2) each item in the list has resolver accessors pre-wired and returning correct values; (3) a type with malformed metadata JSONB is included in the list with defaults, not excluded; (4) resolver is called exactly once per activity type during cache population (not on each consumer read); (5) activity registration wizard obtains expense eligibility from cached item without instantiating resolver; (6) Bufdir export module reads Bufdir metadata fields from cached items correctly. Integration test: full round-trip from Supabase mock → repository → resolver → cache → consumer accessor.