Use idiomatic Effect time and random in orchestration

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What Changed

• Replaced orchestration engine global Date/Date.now() usage with DateTime.now, including command timing metrics and rejected receipt timestamps.
• Replaced orchestration event ID generation from crypto.randomUUID() with Random.nextUUIDv4.
• Added focused @effect/vitest coverage for deterministic random seeding and TestClock-backed rejected receipt timestamps.

Why

These changes keep orchestration behavior injectable and testable through Effect services instead of relying on global time/random sources.

UI Changes

Not applicable.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

  

Note

Replace native Date and crypto.randomUUID with Effect time and random in orchestration

• Timestamps in OrchestrationEngine.ts (read model init, queue envelope startedAtMs, metrics durations, rejected receipt acceptedAt) now use DateTime.now via Effect instead of Date.now() / new Date().toISOString().
• Event IDs in decider.ts now use Random.nextUUIDv4 via the new makeEventBase Effect function instead of crypto.randomUUID.
• Both changes make behavior controllable under TestClock and seeded Random, with new tests verifying deterministic output in OrchestrationEngine.clock.test.ts and decider.random.test.ts.
• Behavioral Change: timestamps and UUIDs are now sourced from Effect's clock and random, so any context without an explicit clock/random layer will use Effect's default real-time providers (no functional difference in production).

^{Macroscope summarized 41737ab.}