`isOverhaulMode()` now returns true unless the URL carries
`?legacy=1`. The overhaul UI from S2-S4 (mode tabs + Mode A
search + Mode B wizard + shared result view) becomes the default
landing for /tools/fristenrechner; the legacy three-step wizard +
Pathway A/B + cascade is reachable only via the explicit
`?legacy=1` opt-out for the two-week deprecation window before
S6 drops the legacy code paths entirely.
The pre-existing `?overhaul=1` deep links from S2-S4 still
resolve — the detector treats *absence* of `?legacy=1` as
overhaul, so bookmarks stay valid. No sidebar / header / outbound
link change needed: those all point at the bare
`/tools/fristenrechner` URL, which now boots overhaul.
Verified — bun build clean (2971 i18n keys unchanged), 256
frontend tests pass, go build + vet clean.
mAi
4571bd4980