feat: add global update progress

[deltrivx]

Summary

• make the global top-left ThemeEffects version popup use the same async updater as the settings page
• add OTA/full update progress, percentage, stage, rolling log, retry state, and completion/failure actions
• keep update actions in the popup footer's lower-left area
• publish the complete v2.8.7 snapshot and update release metadata

Root cause

The v2.8.6 global popup submitted install_version synchronously and only displayed the initial task message. It did not request async=1 or poll job_status, so users had no progress feedback.

Local Unraid verification

• deployed the changed JS/CSS/Loader files to both flash and runtime directories
• PHP syntax checks passed on Unraid
• exercised an OTA async job on Unraid: 22% -> 70% -> 100%, completed successfully

Checks

• ./scripts/build-release.sh v2.8.7 snapshot
• ./scripts/verify-release.sh v2.8.7
• node --check apps-enhancement.js