Add "Last heard" relative-time data point above map on QSO Details sheet

[patrickrb]

Summary

Adds a Last heard data point to the QSO Details bottom sheet, rendered as a relative "ago" time (just now, 45s ago, 12m ago, 3h ago, 2d ago) positioned above the map. Operators get immediate recency context without mentally computing elapsed time from a raw timestamp.

What changed

• QsoSheet.kt
  • New pure, unit-tested computeLastHeard(utcTimeMillis, nowMillis): LastHeard that buckets elapsed time into a LastHeard sealed type (Unknown/JustNow/Seconds/Minutes/Hours/Days). Kept Compose- and resource-free so it's directly testable and localizable.
  • New thin LastHeardRow composable that maps a bucket to a localized string via lastHeardText and renders the label/value row above QsoPathMap.
  • QsoSheetContent now observes the app's existing MainViewModel.timerSec (~1s UTC heartbeat) and passes it in, so the value refreshes while the sheet is open.
• strings_compose.xml — new qso_last_heard* strings (label + just now / %1$ds ago / %1$dm ago / %1$dh ago / %1$dd ago / -- placeholder).
• LastHeardTest.kt — 7 tests covering every bucket boundary plus the edge cases.

Acceptance criteria

• ✅ Last heard label/value shown above the map.
• ✅ Relative format with ago suffix.
• ✅ Updates as time passes (driven by timerSec, the same clock the decode list uses).
• ✅ Edge cases handled cleanly: missing/non-positive timestamp → --; future timestamp (clock skew) clamps to just now (never negative); very old → plain day count (e.g. 500d ago).

Notes / assumptions

• Thresholds (5 s / 60 s / 60 m / 24 h) mirror the existing decode-row formatTimeAgo so recency reads consistently across the app.
• Timestamp source is Ft8Message.utcTime (epoch ms); "now" is UtcTimer-based timerSec, both already used elsewhere.
• New strings are English-only for now (other locales fall back to the default resource); no lint enforcement of MissingTranslation in this module.

Testing

./gradlew :app:testDebugUnitTest --tests '*.LastHeardTest' --tests '*.QsoSheetLogicTest' → BUILD SUCCESSFUL (7/7 new tests pass; existing sheet tests unaffected). Main source compiles.

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 31.70732% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 22.44%. Comparing base (c2f63e8) to head (5665cb1).
⚠️ Report is 260 commits behind head on dev.

Files with missing lines	Patch %	Lines
...in/kotlin/radio/ks3ckc/ft8af/ui/decode/QsoSheet.kt	31.70%	28 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                dev     #578      +/-   ##
============================================
+ Coverage     21.66%   22.44%   +0.77%     
- Complexity      149      197      +48     
============================================
  Files           163      169       +6     
  Lines         20877    21672     +795     
  Branches       3128     3281     +153     
============================================
+ Hits           4523     4864     +341     
- Misses        16167    16585     +418     
- Partials        187      223      +36     

Flag	Coverage Δ
android	14.67% <31.70%> (+1.53%)	⬆️
native	9.93% <ø> (ø)

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Files with missing lines	Coverage Δ
...in/kotlin/radio/ks3ckc/ft8af/ui/decode/QsoSheet.kt	4.00% <31.70%> (+2.03%)	⬆️

... and 16 files with indirect coverage changes

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[Copilot]

Pull request overview

Adds a “Last heard” relative-time field to the QSO Details bottom sheet (above the path map), backed by a pure bucketing function (computeLastHeard) and localized strings, with unit tests covering bucket boundaries and edge cases.

Changes:

• Introduces LastHeard sealed buckets + computeLastHeard(utcTimeMillis, nowMillis) for relative-time bucketing.
• Renders a new LastHeardRow above QsoPathMap, refreshing using MainViewModel.timerSec.
• Adds Compose string resources and new unit tests for bucket boundaries and edge cases.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
ft8af/app/src/main/kotlin/radio/ks3ckc/ft8af/ui/decode/QsoSheet.kt	Adds “Last heard” UI row and the pure bucketing/localization logic.
ft8af/app/src/main/res/values/strings_compose.xml	Adds localized strings for the new “Last heard” label and relative-time formats.
ft8af/app/src/test/kotlin/radio/ks3ckc/ft8af/ui/decode/LastHeardTest.kt	Adds unit tests covering all bucket thresholds and edge cases.

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