* fix(api): throttle api_keys last_used_at writes in auth middleware
Every API key request spawned a goroutine that ran an UPDATE on
api_keys, so a key driving HLS segments or a polling integration hit the
table with one write per request, and a stalled database could pile
those goroutines up without bound. The jellycompat authenticator already
guards this same write with a once-per-minute throttle per key; the main
middleware was missing it.
Bring the two in line. Track the last write per key ID and only launch
the update once a minute has passed, with a timeout on the background
write. The map is keyed by key ID so it stays bounded.
* fix(auth): bound API key last-used throttling
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Co-authored-by: Quick104 <31828688+Quick104@users.noreply.github.com>
