Fix audio eMOS calculation and display

Summary
- **Fix `v1_summary` to extract inline audio inbound tracks from main events** — inbound audio tracks were embedded inline on main stat events but never iterated over, so `compute_emos` was never called for them. Added `build_track_data` helper and loop over inline tracks per snapshot.
- **Fix `compute_emos` packet loss fallback** — previously required `remote-outbound-rtp` data (which many browsers don't send) for `packetsSent`. Now falls back to `packetsLost / (packetsLost + packetsReceived)` from local `inbound-rtp` stats when remote data is unavailable.
- **Fix `compute_emos` RTT source** — changed RTT lookup from `remote.audio.outbound` (which never carries `roundTripTime`) to `remote.audio.inbound`.
- **Fix `compute_emos` one-way delay** — changed `delay = RTT` to `delay = RTT / 2` per E-model specification.
- **Fix `compute_emos` guards** — added `bitrate 0` guard before `math.log`, `packets_sent 0` and `total_packets == 0` guards, and fixed operator precedence in auxiliary delay (`0.1 * (delay - 150)`).
- **Fix `check_emos_score` shared mutable state** — replaced shared `issue_template` dict with a `make_issue_template()` factory function to prevent cross-participant corruption.
- **Fix `check_emos_score` running average** — replaced incorrect `(avg + score) / 2` with Welford's online mean.
- **Fix event ordering** — added `ORDER BY created_at ASC, id ASC` to `get_stats_events` and removed `events.reverse()`.
- **Add pending track buffer** — per-track events that arrive before their connection's main event are queued and flushed when the snapshot is created.
- **Add `@staticmethod` to `get_stats_events`**.

Test plan
- [x] Verified eMOS scores computed for Chrome and Edge participants across multiple test calls
- [x] Verified packet loss fallback produces correct scores when `remote-outbound-rtp` is absent
- [x] Verified zero errors in API logs during summary building
- [x] Verified `check_emos_score` correctly accumulates per-participant averages

Author: Mupati