Keep shadow order identities unique within one clock tick #117

Affected version: 0.1.2; public main 43fc66f. Environment: Python 3.12, offline provider transports.

Observed behavior: Millisecond timestamp identities collide for two accepted orders.

Expected behavior and acceptance: Two accepted shadow orders in the same clock tick must retain distinct identities in the returned orders and execution journal, including reduction orders.

Verify a public API or feed workflow fails against the unchanged producing base and passes with the repair. Record exact revisions and commands, run the applicable full quality gates, and preserve failure atomicity. No live-money orders or release actions.

This focused issue owns one repair originally reported in #111 and proposed in #112. Retain the original contributor's attribution. The bundled report remains open until all five independent problems are substantively resolved.

AI assistance: Codex prepared this focused maintenance issue from the existing report.