fix: harden tenant-scoped revenue reporting

[Taqi20]

Summary

Fixes tenant isolation and revenue reporting issues in the property dashboard.

Changes

• Restores database-backed revenue calculation using DATABASE_URL.
• Removes the unsafe tenant-agnostic mock fallback.
• Adds tenant isolation to Redis revenue cache keys.
• Enforces property ownership in the backend.
• Scopes dashboard properties by tenant.
• Preserves decimal revenue values in API responses.
• Handles currency grouping safely.
• Adds timezone-aware monthly revenue calculation using the property timezone.
• Preserves tenant identity for local authentication.

Validation

• Tenant-specific revenue behavior verified.
• Property ownership checks verified.
• Tenant-scoped dropdown verified.
• Decimal and currency handling verified.
• Timezone-aware monthly calculation verified.
• Backend syntax checks passed.
• Frontend production build passed.