chore(js-ts): Convert index.js to TypeScript

[devin-ai-integration]

Summary

Migrates the root-level index.js application entry point to TypeScript as part of the ongoing JavaScript to TypeScript migration effort.

Architecture

Due to Metro bundler and CI scripts expecting index.js as the entry file, this PR uses a wrapper pattern:

• index.js - Thin wrapper that imports from the TypeScript entry point (required for Metro bundler compatibility)
• app/entry.ts - Contains all the actual application initialization logic in TypeScript

Changes:

• Created app/entry.ts with all entry point logic converted to TypeScript
• Simplified index.js to a single import statement
• Added type declaration for global.ErrorUtils (React Native's global error handler)
• Updated ESLint disable comments to use TypeScript-specific rules
• Removed unused ErrorUtils import from react-native (now using typed global.ErrorUtils)
• Added type cast for handleCustomError to match ErrorHandlerCallback type
• Updated import paths in app/entry.ts for the new location

Review & Testing Checklist for Human

• Verify the app starts correctly - This is the application entry point; any issues here will prevent the app from launching
• Review the handleCustomError as ErrorHandlerCallback type cast (app/entry.ts line 113) - This is a workaround for a pre-existing type mismatch where handleCustomError expects (Error, boolean) but ErrorHandlerCallback expects (any, boolean?). The cast is safe but worth noting.
• Verify import paths in app/entry.ts are correct (e.g., ../shim.js, ./util/sentry/utils, ../app.config.js)
• Run the app locally with yarn watch and test basic functionality to ensure error handling still works

Recommended Test Plan

1. Run yarn watch and verify the app launches without errors
2. Trigger an error to verify global error handling still works
3. Verify Sentry integration is functional

Notes

• CI Status: build, js-bundle-size-check, and all 10 unit-tests shards pass ✅
• The lint and lint:tsc CI jobs were cancelled but verified locally before pushing
• Failed CI checks (audit:ci, check-pr-labels, CLABot, sonar-cloud-quality-gate-status) are unrelated to this migration
• Link to Devin run: https://app.devin.ai/sessions/d07420b7b3674b779d3097f6fbdad30f
• Requested by: @joao-cognition

[devin-ai-integration]

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