feat: unified fiscal coverage - PIS/COFINS applicability + conditional RTC in one definition, one queue, one panel

- central/app/unified_fiscal_coverage.py: pure rules (PIS/COFINS NOT_APPLICABLE/REQUIRED/OPTIONAL/NEEDS_REVIEW, RTC only when the ERP switch is on)
- agent: read-only loader (unified_fiscal.py) replaces the legacy/expanded module; findings feed the single operational state, coverage and blocker queue
- hub: BLOCKED_FISCAL_DATA blockers (PIS/COFINS/RTC) share the queue; stale ones close on the next full pass; dashboard breakdown gains CEST/PIS/COFINS/RTC
- panel: legacy/expanded coverage block removed; discreet 'Reforma Tributaria: Ativa/Desativada'
- docs: unified_fiscal_completeness, pis_cofins_applicability, rtc_pis_cofins_model + official source manifests; read-only E2E script

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -44,3 +44,4 @@ scripts/_*
 *.gz
 *.pkl
 .pytmp/
+sources_cache/legal/