[FSSDK-12092] add platform verification for imports

[raju-opti]

Summary

This PR implements a comprehensive platform isolation system for a multi-platform JavaScript SDK that supports Browser, Node.js, and React Native. The system enforces that platform-specific code cannot be imported by incompatible platforms, preventing runtime errors when bundling for different targets.

Key changes:

• Adds validation scripts that check __platforms exports and import compatibility
• Adds script to automatically add __platforms exports based on file name
• Integrates ESLint rule to enforce platform declarations at development time
• Adds extensive documentation and troubleshooting guides
• Updates all source files to include __platforms exports

Test plan

• extensive manual testing

Issues

• FSSDK-12092

[coveralls]

coverage: 77.752% (-0.6%) from 78.387%
when pulling c7be4d4 on raju/platform_validator
into 860fca0 on master.

[Copilot]

Pull request overview

This PR implements a comprehensive platform isolation system for a multi-platform JavaScript SDK that supports Browser, Node.js, and React Native. The system enforces that platform-specific code cannot be imported by incompatible platforms, preventing runtime errors when bundling for different targets.

Key changes:

• Adds validation scripts that check __platforms exports and import compatibility
• Integrates ESLint rule to enforce platform declarations at development time
• Adds extensive documentation and troubleshooting guides
• Updates all source files to include __platforms exports

Reviewed changes

Copilot reviewed 141 out of 142 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
scripts/validate-platform-isolation.js	Main validation script that enforces platform isolation rules
scripts/platform-utils.js	Shared utilities for platform extraction and validation
scripts/test-validator.js	Test suite for platform compatibility rules
scripts/add-platform-exports.js	Auto-fix script to add missing __platforms exports
.platform-isolation.config.js	Configuration for include/exclude patterns
eslint-local-rules/require-platform-declaration.js	ESLint rule enforcing __platforms exports
lib/platform_support.ts	Type definition for valid platforms
vitest.config.mts	Adds coverage configuration
docs/PLATFORM_ISOLATION.md	Comprehensive platform isolation documentation
package.json	Adds validation scripts and new dependencies
lib/**/*.ts	Adds __platforms exports to all source files

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