feat(supertasks): add "skip completed pretasks" option to apply-hashlist form

[linuxkd]

Summary

Adds the client-side control for the server-side supertask dedup feature (server PR hashtopolis/server#2177, feature request hashtopolis/server#2167).

A "Skip pretasks already completed" checkbox is added to the apply-supertask ("Use Supertask") form. When checked, it sends skipCompleted: true to the createSupertask helper and surfaces the server's meta.skippedPretasks response — an info toast listing the skipped pretasks, plus the all-skipped (taskWrapperId == null, no wrapper created) case. Defaults off, so existing behavior is unchanged.

Depends on

• Server: feat(supertask): skip pretasks already completed against the hashlist server#2177 — adds the skipCompleted flag and the meta.skippedPretasks response. This UI is a no-op against a server without that change (the flag is simply ignored).

Changes

• applyhashlist.component.ts — adds a skipCompleted FormControl (buildForm() + initForm()), sends it in the createSupertask body, types the call ResponseWrapper<CreateSupertaskMeta>, surfaces meta.skippedPretasks and the all-skipped case via AlertService, and uses the { next, error, complete } subscribe form (resets isCreatingLoading on error/complete).
• applyhashlist.component.html — the checkbox + explanatory tooltip.

Testing

• Compiles clean under ng serve.
• Verified end-to-end against the server branch with a live CPU agent through this UI: applying a supertask with the box checked skipped the already-exhausted pretask, and only the new pretask ran (and cracked the hash). Screenshots on [FEATURE]: Skip pretasks already completed against the target hashlist when assigning a supertask server#2167.

Refs hashtopolis/server#2167