Add comprehensive documentation for DMARQ, including user guides, deployment instructions, and feature descriptions

- Created main documentation index and user guide with sections on getting started, dashboard overview, managing domains, and reports.
- Added detailed deployment guide for Docker and manual installation.
- Included user-friendly explanations of DMARC, its benefits, and how to manage domains and reports.
- Implemented visual assets for dashboard, domains, IMAP, and reports.
- Established requirements for documentation build using MkDocs and Material theme.
- Integrated navigation structure for easy access to all documentation sections.

backend/app/models/domain.py

@@ -1,7 +1,7 @@
 from typing import List, Optional
 from datetime import datetime
 
-from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String, Text
+from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String, Text, Index
 from sqlalchemy.orm import relationship
 
 from app.core.database import Base
@@ -15,25 +15,35 @@ class Domain(Base):
     id = Column(Integer, primary_key=True, index=True)
     name = Column(String, unique=True, index=True, nullable=False)
     description = Column(Text, nullable=True)
-    active = Column(Boolean, default=True)
+    active = Column(Boolean, default=True, index=True)
     
     # DMARC policy information
-    dmarc_policy = Column(String, nullable=True)
+    dmarc_policy = Column(String, nullable=True, index=True)
     spf_record = Column(String, nullable=True)
     dkim_selectors = Column(String, nullable=True)  # Comma-separated list of DKIM selectors
     
     # DNS verification status
-    verified = Column(Boolean, default=False)
+    verified = Column(Boolean, default=False, index=True)
     verification_token = Column(String, nullable=True)
     
     # Date fields
-    created_at = Column(DateTime, default=datetime.utcnow)
+    created_at = Column(DateTime, default=datetime.utcnow, index=True)
     updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
     
     # Relationships
     reports = relationship("DMARCReport", back_populates="domain", cascade="all, delete-orphan")
     user_domains = relationship("UserDomain", back_populates="domain", cascade="all, delete-orphan")
     
+    # Indexes for common queries
+    __table_args__ = (
+        # Index for finding active and verified domains
+        Index('ix_domains_active_verified', 'active', 'verified'),
+        # Index for finding domains by policy
+        Index('ix_domains_policy', 'dmarc_policy'),
+        # Index for finding recently updated domains
+        Index('ix_domains_updated', 'updated_at'),
+    )
+    
     def __repr__(self):
         return f"<Domain {self.name}>"