#4463 fix(ios): own idle snapshot bridge socket errors

Summary

Own snapshot bridge socket errors through idle handoff and disposal. Retire only the matching connection, use the acquired socket, and preserve close refusal priority. Three files changed. Fixes #4424; umbrella #4368.

Validation

Head 721aa6815ffcae358509ca3a476979dd921076da; base/merge-base 9cbbae2c857d5ce2915b0fe3f8953999c967d2c8.

• Pinned11.17 install/build passed; focused68 passed. Single affected run passed all eight runnable checks: exactCommit=true, checkoutChanged=false, failOpen=false, clean before/after. Related341 passed; full-unit fallback19,341 passed/zero failed/three skipped (names unavailable).
• Provider integration deduplicated against related tests. Coverage/macOS replay were GitHub-owned; iOS replay/device replay parked/manual. Current-head CI, including Coverage, Integration and Android/iOS/macOS/Linux smoke, passed. Apex approves; Cubic reports no issues. GitHub reports MERGEABLE/CLEAN. Conditional skips are not passes.
• Rebase preserved both bridge patches; main supplies the superseded sentinel fix. Fresh source review found no findings. Originalfb2 regression:49 head/restored passes, base detected one failure/unhandled socket error. Historical #4462 receipts remain failed; this new-head pass does not explain their cause.
• Current-head live Settings AX snapshots recovered after a verified idle socket close and helper termination under the same daemon identity. Post-write socket fault produced typed transport-failure/bridge-connection-closed and normal runner fallback; relaunch restored AX for the new generation. Debugger instrumentation is not kernelRST/native-delivery proof. Cleanup completed; late inspection observed the configured60s idle closure and retains its overly strict assertion failure. See the detailed PR evidence comment.