This reverts commit 6a28344. Restore the once-a-day anonymous PostHog heartbeat
and its opt-out toggle: telemetry.go (sendTelemetryHeartbeat, GetTelemetryEnabled/
SetTelemetryEnabled, PostHog host + API key), the startup goroutine, the Settings
→ General toggle + i18n keys, and the README/wiki mentions. version.go is dropped
again (appVersion moves back into telemetry.go). release.ps1 (untracked) pointed
back at telemetry.go by hand.
The matching "five rules" were already documented; add the parts that were only
in code: the per-QSO Explain trace (Test a callsign in the award editor), the
Missing-refs gap finder (in-scope-but-no-reference + bulk assign), how one QSO
credits several references (n-fer POTA / VUCC grid lines, comma/semicolon split),
code-vs-exact matching, and how built-in award updates skip awards you've edited.
Drop the once-a-day anonymous "app_opened" heartbeat to PostHog and everything
around it: telemetry.go (sendTelemetryHeartbeat, GetTelemetryEnabled/
SetTelemetryEnabled, install-ID/last-sent settings keys, PostHog host + API key)
and the startup goroutine that fired it. The 'Send anonymous usage statistics'
toggle is removed from Settings → General (TelemetryToggle + i18n keys), and the
telemetry mentions are stripped from the README and wiki.
appVersion (still used by changelog/update/livestatus/log-email) moves to a new
version.go; release.ps1 now rewrites it there instead of telemetry.go.
rouggy