Add admin-frontend and user-frontend standalone projects, certification/invoice/discovery features, fix auth header and theme consistency

backend/app/models/invoice.py

@@ -0,0 +1,41 @@
+from sqlalchemy import Column, String, Boolean, Integer, DateTime, Text, Float, ForeignKey, Enum as SAEnum
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from app.database import Base
+import uuid
+import enum
+
+
+class InvoiceType(str, enum.Enum):
+    individual = "individual"
+    enterprise = "enterprise"
+
+
+class InvoiceStatus(str, enum.Enum):
+    pending = "pending"
+    issued = "issued"
+    rejected = "rejected"
+
+
+class Invoice(Base):
+    __tablename__ = "invoices"
+
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    user_id = Column(UUID(as_uuid=True), ForeignKey("users.id"), nullable=False, index=True)
+    certification_id = Column(UUID(as_uuid=True), ForeignKey("certifications.id"), nullable=True)
+
+    invoice_type = Column(SAEnum(InvoiceType), nullable=False)
+    title = Column(String(255), nullable=False)
+    tax_id = Column(String(30))
+    amount = Column(Float, nullable=False)
+
+    status = Column(SAEnum(InvoiceStatus), default=InvoiceStatus.pending)
+    reject_reason = Column(Text)
+    issued_at = Column(DateTime)
+
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    user = relationship("User")
+    certification = relationship("Certification")