Migrate Backend to Strict TypeScript

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TypeScript Strict Mode Migration & Type Safety Enhancement

Description

This PR implements a comprehensive TypeScript migration to enable strict type checking and enhance type safety across the LaunchDarkly React application. The changes transform the codebase from a loose TypeScript configuration to a fully strict, type-safe implementation with comprehensive monitoring and validation.

Motivation

• Eliminate Runtime Type Errors: Enable strict TypeScript compiler options to catch type issues at compile time rather than runtime
• Improve Developer Experience: Provide better IDE support, autocomplete, and refactoring capabilities through stronger typing
• Enhance Code Quality: Establish type safety as a foundation for maintainable, scalable code
• Enable Future Refactoring: Create a robust type system that supports safe refactoring and feature development

Key Changes

TypeScript Compiler Enhancements (Click to expand)

• ✅ Enable noImplicitAny: Require explicit type annotations, eliminating implicit any types
• ✅ Enable strictNullChecks: Prevent null/undefined errors by making null checks explicit
• ✅ Enable strictFunctionTypes: Ensure function parameter types are checked strictly
• ✅ Enable noImplicitReturns: Require explicit return statements in all code paths
• ✅ Add Type Coverage Monitoring: Implement automated type coverage tracking and reporting

Type System Improvements (Click to expand)

• 🔐 Branded Types for IDs: Create type-safe ID types to prevent ID mixing across different entities
• 🛡️ Runtime API Validation: Add runtime type checking for API boundaries
• 🏗️ Generic CRUD Interface Patterns: Establish reusable, type-safe CRUD operation interfaces
• 🔌 Type-Safe Event System: Implement strongly-typed event handling interfaces
• 📡 Strict RPC Interface Definitions: Create type-safe RPC communication contracts

Code Quality & Tooling (Click to expand)

• 📏 ESLint TypeScript Rules: Add comprehensive TypeScript-specific linting rules
• 🏛️ Component Boundary Typing: Strengthen type safety at component interfaces
• 🎯 Explicit Return Types: Add explicit return type annotations for better code clarity
• 👀 Class Member Accessibility: Define clear accessibility modifiers for class members
• 📦 TypeScript Project References: Configure modular TypeScript compilation

Impact

• Files Changed: 9,358 files with 1.5M+ lines of code affected
• Type Safety: Comprehensive elimination of implicit any types and runtime type errors
• Developer Productivity: Enhanced IDE support and development experience
• Code Quality: Established foundation for maintainable, type-safe code
• Monitoring: Automated type coverage tracking to maintain type safety standards

Migration Monitoring

This PR includes comprehensive migration monitoring tools:

• Type coverage tracking with automated reporting
• Migration progress monitoring scripts
• Implicit any detection and elimination tools
• Detailed migration history and progress documentation

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