fix(proxies): share the refusal store across duplicated server module copies

[maxmad64bis]

⚠️ base-red inherited: #15306

Summary

The server bundle can hold several copies of the refusal store, one per module graph, so failures recorded by the patched global fetch never reached the account rotation that reads the store: repeated connection resets through one egress kept serving it. The store and its listener list now live in one process-wide object, the pattern already used for the fetch capture context.

Related Issues

• Related to fix(proxies): set aside egress after repeated transport failures with cross-egress success #14802
• Related to fix(sse): share applied proxy capture across duplicated fetch modules #14620

Validation

• Change type: routing
• 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/proxy-refusal-memory-single-instance.test.ts (new, 4 cases: distinct modules witness, cross-copy set-aside visibility, cross-copy transport evidence, cross-copy slow evidence)
• tests/unit/proxy-transition-bridge-single-emit.test.ts (new, 1 case: two bridge copies, one proxy.set_aside emission)

Coverage Notes

• open-sse/utils/proxyRefusalMemory.ts: covered by the single-instance tests (cross-copy reads after writes through another copy)
• open-sse/utils/proxyTransitionListeners.ts: covered by both new test files (shared listener set, idempotent keyed subscription)
• src/lib/proxyEvents/proxyTransitionBridge.ts: covered by the single-emit test (stable subscription key)

Reviewer Notes

• Behavior: The shared object holds data only; per-copy environment reads and TTL caches are untouched.
• Merge: With feat(proxies): log refusal-store writes and expose transport evidence in pool visibility #15374 and fix(proxies): set aside region-refused members briefly #15383 (shared refusal-store files): either order.