fix(traffic): support Prometheus counters with _total suffix

[rmtshnik]

Summary

• accept both legacy telemt_user_octets_* and Prometheus-standard *_total metrics
• update global, per-user, quota, reporting, and reset parsers
• update the traffic regression fixture to match current Telemt output

Problem

Telemt 3.5.7 exports byte counters with the _total suffix. The existing matchers require an opening brace immediately after the base metric name, so traffic remains at zero even though connection metrics continue to work.

Verification

• verified against live Telemt 3.5.7 metrics
• deployed on a test server; per-user counters and Telegram statistics update correctly
• git diff --check passes

Local Bash tests could not be executed on the Windows development host.