fix(sse): use applied egress key for pool-served proxyless accounts

[maxmad64bis]

⚠️ base-red inherited: #14547

Summary

Proxyless accounts served through a shared connection pool retry through the wrong egress path: the rotation keys retries by account fingerprint instead of the egress address the pool actually served, so per-address throttle and set-aside memory never match on retry. The applied egress key (the address the pool served) is now threaded through rotation, throttle and park/resume, so retries hit the same throttle slot and refusal memory as the first attempt. Flag-off behavior is byte-identical.

Related Issues

No linked issue — pool-served proxyless egress keying has no prior ticket.

Validation

• Change type: sse
• Focused tests and category gates from the golden path
• npm run lint
• Reconciled with the current active release base; focused checks rerun afterward
• Production-code changes include a new or updated automated test in this PR

Tests Added Or Updated

• tests/unit/opencode-applied-egress-key.test.ts (new, 10 tests): semaphore isolation per key, set-aside drain with fallback, dedicated-proxy byte-identical keys, park replay legs, cooldown handling; 10/10 green on the rebuilt head.

Coverage Notes

• New rotation/throttle/park branches covered by the new suite; no coverage movement beyond the new branches.

Reviewer Notes

• Parent of a stacked pair: feat(sse): record per-request added wait with cause in call logs #14756 (fix/request-added-wait) sits on top — merge this PR first, then the child.
• The // prettier-ignore is removed; the helper lives in opencodeEgressThrottle.ts under its cap.