fix(frontend): stabilize admin execution pagination bar

[Raja-Hamid]

What changes were proposed in this PR?

The Admin → Executions page had an inconsistent, "jumpy" page-number bar compared to every other list in the app (#3586).

Root cause. It was the only paginated page that re-ran its entire query every second via setInterval(() => this.ngOnInit(), 1000) while driving a manual server-side pager ([nzFrontPagination]="false" with bound [nzPageIndex]/[nzPageSize]/[nzTotal]). Every tick reassigned the data and total under the pager, with no request cancellation, so the bar reshuffled every second and raced the user's clicks. Separately, onQueryParamsChange used an else-if that dropped the page index whenever the page size changed, desyncing the highlighted page from the data.

Fix (frontend-only, admin-execution.component.ts):

• The 1s interval now only ticks the client-side elapsed-time/status of already-loaded rows (updateTimeStatus()); data is refreshed by a decoupled 5s switchMap-cancelled poll that refetches only the current page, never touches page index/size, and updates the total only when it actually changed.
• Rewrote onQueryParamsChange to read page size and index from every event and clamp the page into range (order-independent) — fixing the size-change desync and the out-of-range/empty cases.
• Split fetchData() (user-initiated) and fetchCurrentPage() (background/silent); kill/pause/resume now trigger a prompt refresh instead of waiting for the next tick.

Before: the bar flickered/reshuffled every second and could jump on click or page-size change.
After: the bar is stable when idle, follows clicks, re-centers predictably, and clamps correctly on page-size change — consistent with the rest of the app (e.g. Admin → Users).

Any related issues, documentation, discussions?

Closes #3586

How was this PR tested?

Unit tests (Vitest) — added 8 cases in admin-execution.component.spec.ts covering first/last page, page-size change, order-independent size+index change, single-page, empty results, and no-double-fetch on sort/filter:

corepack yarn ng test --watch=false --include="**/admin-execution.component.spec.ts"
→ 10/10 passing (8 new + 2 existing). Three of the new cases were red against the old code (page-size-change desync, order-independent size+index change, empty-results clamp) and green after the fix.

Manual — ran the bin/single-node stack + ng serve, seeded ~65 workflows/executions, and verified on Admin → Executions that the page bar follows clicks, re-centers, stays idle-stable, and clamps on page-size change; compared side-by-side against Admin → Users (built-in pager) — now consistent.

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Yes, alongside Claude Code

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