refactor(time): make clocks and timers injectable across services, SDK, and web

[CemAyyildiz]

Summary

• Adds @sub-rosa/time with Clock and Scheduler contracts, production (systemClock / systemScheduler) and deterministic fake implementations for tests.
• Migrates first-party runtime code in the SDK, keeper, agent, web app, tlock, receipt-cli, and operational scripts to injected time dependencies with production-safe defaults.
• Adds scripts/check-direct-time-access.mjs to block new direct Date.now / timer usage outside the approved time package adapters.

Scope

• Service, SDK, hook, and script boundaries accept optional time / clock / scheduler overrides.
• React hooks and UI components cancel timers on cleanup; keeper status server clears shutdown timers.
• Time-sensitive unit tests use FakeClock / FakeScheduler instead of real sleeps where practical.
• Stellar SDK transaction .setTimeout(N) calls are unchanged and excluded from the guard.

Closes #239

Test plan

• pnpm time:test
• pnpm time:guard and pnpm time:guard:test
• pnpm --filter @sub-rosa/sdk test and pnpm --filter @sub-rosa/sdk typecheck
• pnpm --filter @sub-rosa/keeper test and pnpm --filter @sub-rosa/keeper typecheck
• pnpm --filter @sub-rosa/agent test
• pnpm --filter @sub-rosa/web test
• pnpm --filter @sub-rosa/tlock test

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