[n-lark]

Description

Fixes the chart slowdown from moving reads onto the store.

Every chart point was a proxy, so filters read points through proxies and every 60th trim re-cloned the series. Now points are stored plain and wrapped only when read, as Vue 3 does, and trims are exact on every message without cloning. Other values are unchanged.

µs, 4 lines	main	Before	After
Time window, 1,000/line	44	221	45
Time window, 5,000/line	129	1,517	234
Point limit, 5,000/line	1,339	1,151	461
Page load, 1,000/line	2,373	5,561	2,491

Contract changes

• A stored message's _datapoint is the same object as the chart's point, not the same proxy. Writes are still reported; match points by value, not ===.
• filter / keepLatestPerTopic callbacks get plain points, so changing them isn't reported (as on main). No third-party widget calls filter.

Related Issue(s)

Resolves #2322

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production
• Link to Changelog Entry PR, or note why one is not needed.

Labels

• Includes a DB migration? -> add the area:migration label