fix: make workflow event hash platform-deterministic

The hash included `ts` in the input despite the docstring promising
it was "independent of ts/actor/session". On Windows, millisecond
timer resolution caused two calls within the same tick to get
different timestamps, producing different hashes for identical
cmd+params.

Remove `ts` from the hash input to match documented behavior.
Revert continue-on-error on windows-portability now that the
root cause is fixed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -144,7 +144,6 @@ jobs:
 
   windows-portability:
     timeout-minutes: 15
-    continue-on-error: true
     needs: detect-changes
     if: >-
       needs.detect-changes.outputs.docs-only != 'true'

src/resources/extensions/gsd/workflow-events.ts

@@ -40,7 +40,7 @@ export function appendEvent(
   event: Omit<WorkflowEvent, "hash" | "session_id"> & { actor_name?: string; trigger_reason?: string },
 ): void {
   const hash = createHash("sha256")
-    .update(JSON.stringify({ cmd: event.cmd, params: event.params, ts: event.ts }))
+    .update(JSON.stringify({ cmd: event.cmd, params: event.params }))
     .digest("hex")
     .slice(0, 16);