Finalize Yieldstar integration error handling

[djgrant]

Summary

• Route reconciler log events by event.level, ensuring coordination-waiting and every future warning-level event use logger.warn.
• Replace command-local process.exit(1) calls with one testable async Commander error boundary that returns the CLI exit status.
• Consolidate plan, deploy, and destroy credential failures through the same command-specific guidance while preserving non-credential error logging.

Review findings addressed

• Added focused regression coverage for the durable reconciler.coordination.waiting warning event.
• Added credential and non-credential command-boundary failure tests.
• Preserved deployment store-prefix isolation, the durable coordination-waiting event, destroy handling, and the existing durable execution, replay, store CAS, coordination, and destroy semantics.
• Confirmed Notation-owned terminology uses Yieldstar; upstream identifiers and package names remain unchanged.

Validation

• pnpm build
• pnpm typecheck
• pnpm test:once (79 passed, 4 skipped)
• Focused reconciler logger and CLI error-boundary tests
• Prettier check for all changed source and test files
• git diff --check
• Markdown physical-line audit (the stacked implementation diff changes no Markdown files)
• Yieldstar terminology audit

Upstream release risk (not patched in Notation)

The installed @yieldstar/sqlite-runtime 0.5.0 task queue writes Date.now() + VISIBILITY_WINDOW milliseconds to visible_from, while its SQL visibility queries compare that value with strftime('%s', 'now') Unix seconds. If a worker crashes after taking a task, the task can remain hidden for roughly 55,000 years. This requires an upstream release fix; this PR intentionally contains no Notation patch, workaround, fallback, lease, or refresh path.

[djgrant]

Superseded by the squashed two-PR stack: #42 (reconciliation foundation) and #43 (runtime and CLI cutover). The combined result of that stack is byte-identical to this stack's final tree.