Add organization management and admin-specific APIs

- Introduced schemas for organizations, including creation, updates, and responses.
- Created models for `Organization` and `UserOrganization` with role-based access control and relationships.
- Implemented admin APIs for managing users, organizations, and bulk actions.
- Added advanced filtering, sorting, and pagination for user and organization queries.
- Updated `CRUD` logic to support organization-specific operations and member management.
- Enhanced database with necessary indexes and validation for improved performance and data integrity.

backend/app/schemas/organizations.py

@@ -0,0 +1,154 @@
+# app/schemas/organizations.py
+import re
+from datetime import datetime
+from typing import Optional, Dict, Any, List
+from uuid import UUID
+
+from pydantic import BaseModel, field_validator, ConfigDict, Field
+
+from app.models.user_organization import OrganizationRole
+
+
+# Organization Schemas
+class OrganizationBase(BaseModel):
+    """Base organization schema with common fields."""
+    name: str = Field(..., min_length=1, max_length=255)
+    slug: Optional[str] = Field(None, min_length=1, max_length=255)
+    description: Optional[str] = None
+    is_active: bool = True
+    settings: Optional[Dict[str, Any]] = {}
+
+    @field_validator('slug')
+    @classmethod
+    def validate_slug(cls, v: Optional[str]) -> Optional[str]:
+        """Validate slug format: lowercase, alphanumeric, hyphens only."""
+        if v is None:
+            return v
+        if not re.match(r'^[a-z0-9-]+$', v):
+            raise ValueError('Slug must contain only lowercase letters, numbers, and hyphens')
+        if v.startswith('-') or v.endswith('-'):
+            raise ValueError('Slug cannot start or end with a hyphen')
+        if '--' in v:
+            raise ValueError('Slug cannot contain consecutive hyphens')
+        return v
+
+    @field_validator('name')
+    @classmethod
+    def validate_name(cls, v: str) -> str:
+        """Validate organization name."""
+        if not v or v.strip() == "":
+            raise ValueError('Organization name cannot be empty')
+        return v.strip()
+
+
+class OrganizationCreate(OrganizationBase):
+    """Schema for creating a new organization."""
+    name: str = Field(..., min_length=1, max_length=255)
+    slug: str = Field(..., min_length=1, max_length=255)
+
+
+class OrganizationUpdate(BaseModel):
+    """Schema for updating an organization."""
+    name: Optional[str] = Field(None, min_length=1, max_length=255)
+    slug: Optional[str] = Field(None, min_length=1, max_length=255)
+    description: Optional[str] = None
+    is_active: Optional[bool] = None
+    settings: Optional[Dict[str, Any]] = None
+
+    @field_validator('slug')
+    @classmethod
+    def validate_slug(cls, v: Optional[str]) -> Optional[str]:
+        """Validate slug format."""
+        if v is None:
+            return v
+        if not re.match(r'^[a-z0-9-]+$', v):
+            raise ValueError('Slug must contain only lowercase letters, numbers, and hyphens')
+        if v.startswith('-') or v.endswith('-'):
+            raise ValueError('Slug cannot start or end with a hyphen')
+        if '--' in v:
+            raise ValueError('Slug cannot contain consecutive hyphens')
+        return v
+
+    @field_validator('name')
+    @classmethod
+    def validate_name(cls, v: Optional[str]) -> Optional[str]:
+        """Validate organization name."""
+        if v is not None and (not v or v.strip() == ""):
+            raise ValueError('Organization name cannot be empty')
+        return v.strip() if v else v
+
+
+class OrganizationResponse(OrganizationBase):
+    """Schema for organization API responses."""
+    id: UUID
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+    member_count: Optional[int] = 0
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class OrganizationListResponse(BaseModel):
+    """Schema for paginated organization list responses."""
+    organizations: List[OrganizationResponse]
+    total: int
+    page: int
+    page_size: int
+    pages: int
+
+
+# User-Organization Relationship Schemas
+class UserOrganizationBase(BaseModel):
+    """Base schema for user-organization relationship."""
+    role: OrganizationRole = OrganizationRole.MEMBER
+    is_active: bool = True
+    custom_permissions: Optional[str] = None
+
+
+class UserOrganizationCreate(BaseModel):
+    """Schema for adding a user to an organization."""
+    user_id: UUID
+    role: OrganizationRole = OrganizationRole.MEMBER
+    custom_permissions: Optional[str] = None
+
+
+class UserOrganizationUpdate(BaseModel):
+    """Schema for updating user's role in an organization."""
+    role: Optional[OrganizationRole] = None
+    is_active: Optional[bool] = None
+    custom_permissions: Optional[str] = None
+
+
+class UserOrganizationResponse(BaseModel):
+    """Schema for user-organization relationship responses."""
+    user_id: UUID
+    organization_id: UUID
+    role: OrganizationRole
+    is_active: bool
+    custom_permissions: Optional[str] = None
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class OrganizationMemberResponse(BaseModel):
+    """Schema for organization member information."""
+    user_id: UUID
+    email: str
+    first_name: str
+    last_name: Optional[str] = None
+    role: OrganizationRole
+    is_active: bool
+    joined_at: datetime
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class OrganizationMemberListResponse(BaseModel):
+    """Schema for paginated organization member list."""
+    members: List[OrganizationMemberResponse]
+    total: int
+    page: int
+    page_size: int
+    pages: int