fix: Regional collector URLs, drop bitrate attributes before start, HEARTBEAT timing, and build fixes

[avinash-newrelic]

Summary

• Regional Collector URLs: Fixed collector endpoint configuration
• Drop Bitrate Attributes Before Start: Prevent sending bitrate attributes before content start event
• HEARTBEAT Timing: Fixed HEARTBEAT event to trigger at elapsed time 0 (after pause/resume scenarios)
• Build Fixes: Resolved lint errors in sample app and core modules
• README Update: Removed pricing information from documentation

Changes

Area	Description
Regional Collectors	Fixed endpoint URLs for all regions
Bitrate Attributes	Drop bitrate attributes before CONTENT_START to prevent invalid data
HEARTBEAT	Trigger HEARTBEAT at elapsed time 0 for accurate timing
Lint	Fixed lint errors across modules
Docs	Removed pricing info from README

Test Plan

• Verify regional collector URLs route correctly
• Confirm bitrate attributes are not sent before CONTENT_START
• Verify HEARTBEAT fires at elapsed time 0 after pause/resume
• Build passes without lint errors