feat: show observation details on track point popup (ERA-13537)

[jeslefcourt]

Summary

Resolves ERA-13537 — customers want to see per-position telemetry (e.g. speed) when clicking a point along a subject's historic track ("snail trail").

Clicking a track timepoint now fetches the underlying observation for that subject + time and exposes its device_status_properties via the same "more details" toggle already used by the subject popup.

Changes

• TimepointPopup now fetches the observation by subject_id over a small time window bracketing the point, then selects the matching record. Matching is done by instant, not string: the track endpoint serializes times in UTC (...+00:00) while observation recorded_at uses the tenant-local offset (...-07:00) — the same instant, different string. A closest-in-window fallback handles sub-second rounding (track times are whole-second; recorded_at carries milliseconds).
• New shared AdditionalDeviceProperties component extracts the toggle + device_status_properties list + localStorage persistence that previously lived inline in SubjectPopup. Both popups now consume it, so the control stays consistent and the preference is shared.
• SubjectPopup refactored to use the shared component. Its extra behaviors (static-subject gating, time-slider active/empty rendering) are preserved via optional props that default off, so TimepointPopup is unaffected.
• 6px of spacing between the location and the details in the track point popup (collapses when there are no details to show).

Verification

• Unit tests: TimepointPopup (7) + SubjectPopup (5) pass. New tests lock in the instant-vs-string matching and the non-zero query window as regression guards (both fail against the pre-fix code).
• Verified against a live tenant (easterisland): across sampled tracked subjects, the popup resolves the correct observation for a clicked point 8/8, with device properties shown where the observation has them. This live check is what surfaced the two matching bugs (UTC-vs-local string mismatch, and a zero-width since==until query returning nothing), which are fixed here.
• ESLint clean on all touched files.

Notes for reviewers

• The observation query uses a ±1s window; the nearest observation to a track point was always within 999ms in live data. If a source ever emits denser-than-1s data, the exact-instant match still disambiguates.
• AdditionalDeviceProperties returns null when there are no device properties, so no empty control or stray spacing renders.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds telemetry (“device status properties”) to the historic track timepoint popup by fetching the nearest matching observation for the clicked subject/time and reusing the same “more details” UI used in the subject popup.

Changes:

• TimepointPopup now queries /observations for the clicked subject_id within a small time window and matches by instant (with closest-in-window fallback).
• Introduces a shared AdditionalDeviceProperties component that encapsulates the toggle UI, list rendering, and localStorage persistence.
• Refactors SubjectPopup to use the shared component and removes the now-duplicated styles/logic.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/TimepointPopup/index.js	Fetches observations around the clicked timepoint and renders shared additional device properties UI.
src/TimepointPopup/index.test.js	Adds regression coverage for instant-vs-string matching, non-zero query window, and toggle/localStorage behavior.
src/TimepointPopup/styles.module.scss	Adds spacing for the additional properties section in the timepoint popup.
src/AdditionalDeviceProperties/index.js	New shared component for rendering/toggling device status properties with persisted preference.
src/AdditionalDeviceProperties/styles.module.scss	Moves additional device properties list/toggle styles into the shared component.
src/SubjectPopup/index.js	Replaces inline additional properties UI with the shared AdditionalDeviceProperties component.
src/SubjectPopup/styles.module.scss	Removes additional properties styles that were moved into the shared component.