Introduce a telemetry module that exposes a `reportError` helper.
Under the hood it forwards errors to PostHog, but the module is the
only place that knows about PostHog.
Replace `console.error` calls used for error reporting with
`reportError`, so the codebase now goes through a single, consistent
API for telemetry.
This normalizes how errors are reported and makes it straightforward
to swap PostHog for another backend later on, without touching every
call site.
Reorganize all participant list related code elements into a
dedicated feature folder, so related components, hooks and helpers
are grouped together and easier to locate.
lebaudantoine