Fixes#4339. PostHog telemetry was previously enabled by default for every
install, which surprised privacy-conscious users on self-hosted setups.
Behavior for new users only (existing users are migrated to a decision that
preserves their current `telemetryEnabled` setting):
- 90% are silently opted out on first launch.
- 10% see a one-time consent prompt; accepting opts in, declining opts out.
Decision is persisted via a new `readest-telemetry-decision` localStorage key
so subsequent boots don't re-roll. PostHog now inits with
`opt_out_capturing_by_default` so brand-new users never ping before the
decision is finalized.
New `TelemetryConsentDialog` uses the project's `btn-contrast` (theme-neutral)
CTA and `eink-bordered` chassis so it renders correctly under `[data-eink]`
without color-mode-only assumptions. Strings translated across all 33 locales.
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Huang Xin