[FSSDK-12107] refactor build system

[raju-opti]

Summary

• Replaced the TypeScript Rollup plugin with direct tsc compilation followed by pure bundling and updated outdated build tools.
• Created ts-example/ directory with an example typescript project, which is used to check that typescript support is working properly.
• CI Integration: Added ts-check job to GitHub Actions workflow.

Test plan

Issues

• FSSDK-12107

[coveralls]

coverage: 77.745%. remained the same
when pulling a2af367 on raju/build_refacator
into 083562f on master.

[Copilot]

Pull request overview

This pull request refactors the build system by replacing the Rollup TypeScript plugin with direct TypeScript compilation followed by bundling. It also adds a TypeScript example project to verify TypeScript support and integrates a CI check for it.

Changes:

• Replaced rollup-plugin-typescript2 with direct tsc compilation to .build/ directory, then bundling from there
• Updated Rollup plugins to newer versions and migrated from deprecated plugins to @rollup/plugin-terser
• Added ts-example/ directory with comprehensive TypeScript usage examples and test infrastructure

Reviewed changes

Copilot reviewed 12 out of 16 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tsconfig.json	Added importHelpers: true and split output between .build and dist directories
rollup.config.mjs	Refactored to use ES modules, updated plugins, changed input paths to .build/
package.json	Updated build scripts, added tslib, updated plugin dependencies, added ts-example script
package-lock.json	Updated all rollup plugins and rollup itself to latest versions
ts-example/*	New TypeScript example project demonstrating SDK usage patterns
scripts/run-ts-example.js	New script to build SDK and run TypeScript example with datafile server
.github/workflows/javascript.yml	Added ts-check job to CI pipeline
.gitignore	Added .build/ directory to ignore list
lib/index.browser.ts	Removed extraneous blank line

Files not reviewed (1)

• ts-example/package-lock.json: Language not supported

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[Copilot]

The comment at the top of this file says it will be "running at http://localhost:8910" but actually the constant PORT is defined on line 17 as 8910. While this is consistent, if someone changes the PORT constant, they should also update the comment. Consider referencing the PORT constant in the comment or making it dynamically reflect the actual port in the startup message (which it already does on line 46).

Suggested change

	* Runs at http://localhost:8910
	* Runs at http://localhost on the port specified by the PORT constant below