feat(domain): WordCounterService + WordCountResult + ChargeableCharConfig entity + exceptions (PRC-001)
- WordCounterService: pure domain service, 7-step algorithm (null/empty fast path → length check → emoji detection via Rune.EnumerateRunes → count specials before replace → replace specials+hyphens → collapse whitespace → tokenize)
- WordCountResult: sealed record with TotalWords + IReadOnlyDictionary<string,int> SpecialCharCounts
- 4 domain exceptions extending DomainException: EmojiDetectedException, WordCountValidationException, ChargeableCharConfigInvalidException, ChargeableCharConfigForwardOnlyException
- ChargeableCharConfig: rich entity with Create factory (invariants), Rehydrate reconstructor, ScheduleNewPrice (forward-only, returns new entity), Deactivate (idempotent)
- ChargeableCharCategories: enum-as-string constants (Currency, Percentage, Exclamation, Question, Other)
- DomainTimeProviderExtensions: internal GetArgentinaToday helper (mirrors Application.Common without creating Domain→Application dependency)
- 60 new tests: 25 golden cases all GREEN, 12 entity invariant tests, 12 exception tests, 5 WordCountResult tests, 6 ChargeableCharConfig entity tests
dmolinari
ded76fcdc7