fix: use millisecond precision in timestamps

[mattjohnsonpint]

A few places we had only seconds precision. Increasing to milliseconds for consistency.

[Copilot]

Pull Request Overview

This PR updates timestamp formatting from time.RFC3339 to utils.TimeFormat (which includes millisecond precision) across various modules, and records this change in the changelog.

• Replace all .Format(time.RFC3339) calls for StartedAt, UpdatedAt, and event Timestamp with utils.TimeFormat
• Ensure consistency in timestamp precision in DB writes and actor messages
• Add a changelog entry for this fix

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
runtime/db/inferencehistory.go	Updated StartedAt formatting to use millisecond precision
runtime/db/agentstate.go	Switched UpdatedAt formatting in DB read/write methods
runtime/actors/wasmagent.go	Changed actor state UpdatedAt to use utils.TimeFormat
runtime/actors/subscriber.go	Updated event Timestamp formatting for messages
CHANGELOG.md	Added entry for the millisecond-precision fix

Comments suppressed due to low confidence (2)

runtime/db/inferencehistory.go:378

• Add or update a unit test for writeInferenceHistoryToModusDb to assert that StartedAt includes millisecond precision, ensuring utils.TimeFormat is applied correctly.

StartedAt:  data.start.Format(utils.TimeFormat),

CHANGELOG.md:11

• Consider noting any backward compatibility impact of changing timestamp formats in the public API or persisted data, and update consumer-facing documentation accordingly.

- fix: use millisecond precision in timestamps [#892](https://github.com/hypermodeinc/modus/pull/892)