[Workflows] Fix: implement workflows instance methods

[pombosilva]

Fixes #12872 that reverted the original #12814 .

The original PR was causing constant Windows CI errors where the workerd process crashed mid tests.

The problem was with the pause() flow in binding.test.ts tests. Pause makes a void call to waitUntilNothingIsRunning so that running step.do's can finish before actually pausing the instance. The last thing waitUntilNothingIsRunning does is to change the instance status to paused and then aborts the Engine DO. The problem with this is because this is a void call that returns immediately, the actual abort fires later. At that point, no RPC is active and the abort happens in an orphaned context - which makes workerd crash on Windows CI.

The fix was to simply propagate Errors, where pause signals Engine instead of aborting - the key is that the throw must happen from inside the workflow's own promise chain where init() can catch it.

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Original PR main changes:

Implements the 4 missing Workflow instance lifecycle methods for local dev: pause(), resume(), restart(), and terminate().

• Pause: pause() sets WaitingForPause status, then it checks between steps, stores the pause timestamp, transitions to Paused, and aborts the DO. If there are any pending step.do's these will finish before going to Paused.
• Resume: cancels a pending pause (WaitingForPause -> Running), or fully resumes by offsetting priority queue timers by the pause duration and firing init().
• Restart: aborts the DO, then on the fresh instance reads stored INSTANCE_METADATA, cleans up SQL/KV (preserving modifier keys and mocked event data), writes fresh logs, and fires init().
• Terminate: sets status to Terminated and aborts.

Also:

• Validated step configuration.
• Aligned states table schema with production (DATETIME('now','subsec') for timestamp precision).
• WorkflowHandle.status() auto-refreshes stale DO stubs after abort.
  Also:

Validated step configuration.
Aligned states table schema with production (DATETIME('now','subsec') for timestamp precision).
WorkflowHandle.status() auto-refreshes stale DO stubs after abort.

---

• Tests
  • Tests included/updated
  • Automated tests not possible - manual testing has been completed as follows:
  • Additional testing not necessary because:
• Public documentation
  • Cloudflare docs PR(s): Update Workflows local dev methods now working cloudflare-docs#28915
  • Documentation not necessary because:

A picture of a cute animal (not mandatory, but encouraged)

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commit: 7b5437b

[workers-devprod]

Codeowners approval required for this PR:

• ✅ @cloudflare/workflows
• ✅ @cloudflare/wrangler

Show detailed file reviewers

[penalosa]

Looks good from the vitest pool & miniflare side, but this also needs a workflows review