Remove the RepoISO integration; keep generic support for shares of other services

RepoISO now manages the NAS itself, so nasmon no longer polls it (settings field, dashboard card,
menu link and repoiso:* alerts are gone). Drop-in SMB includes, read-only listing and keeping
smbd/nfs-server running for other software's shares stay.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/handlers.go

@@ -465,7 +465,6 @@ func formToSettings(r *http.Request, old config.Settings) config.Settings {
 	c.SelfTests.ShortDays = num("st_short_days", old.SelfTests.ShortDays)
 	c.SelfTests.LongDays = num("st_long_days", old.SelfTests.LongDays)
 	c.SelfTests.Hour = num("st_hour", old.SelfTests.Hour)
-	c.Integrations.RepoISOURL = strings.TrimSpace(r.FormValue("repoiso_url"))
 	return c
 }