feat(logging): add size-limited log rotation via lumberjack

[adamshiervani]

Summary

• Add lumberjack-based log rotation to prevent unbounded last.log growth on long-running devices
• App now writes directly to /userdata/jetkvm/app.log (50 MB max, 1 backup) via a new zerolog multi-writer, independent of the shell redirect in RkLunch.sh
• Log app and system version at startup using NoLevel so it always appears regardless of configured log level

Background

/userdata/jetkvm/last.log grows unbounded for the lifetime of a process run — the only reset is a process restart (shell > truncation). On a device that stays up for months, this can consume significant space on the 13 GB /userdata partition.

The rv1106-system image and the app have independent update paths, so we can't guarantee the shell redirect will be removed when the app is updated. This solution writes to a different file (app.log), making it safe regardless of whether the old redirect is still in place.

Changes

File	Change
go.mod / go.sum	Add gopkg.in/natefinch/lumberjack.v2
internal/logging/logger.go	Add lumberjack writer to multi-writer (guarded: only on device)
internal/supervisor/consts.go	AppLogPath → /userdata/jetkvm/app.log
main.go	Version log changed from Info() to Log() (NoLevel)
ui/e2e/global-teardown.ts	Read app.log instead of last.log
ui/e2e/helpers.ts	restartAppViaSSH redirects to /dev/null
ui/e2e/log-rotation.spec.ts	New e2e tests for log rotation
DEVELOPMENT.md	Updated all log path references

Test plan

• Deploy to device, verify /userdata/jetkvm/app.log is created and contains log output
• Verify app.log contains app_version and system_version fields
• Verify diagnostics zip (GET /diagnostics) includes app.log
• Verify tail -f /userdata/jetkvm/app.log works for live log viewing
• On a device with old system image (redirect still in place), verify both last.log and app.log are written — app.log is authoritative
• Run e2e tests: npx playwright test log-rotation