fix: revert leftover Project→Client mislabels, drop tracked .env.backfill

Rename in 91045a1 was only partially reverted by later commits, leaving
~20 UI spots calling the project entity "Client" while table headers
already said "Project". Reverted all of them plus the /clients/:id
route (now /projects/:id canonical again, nothing was live yet).

Also: stop tracking .env.backfill (had a live admin password/token
committed - rotate those credentials), remove stale pre-redesign
layout.md superseded by REDESIGN-LAYOUT2.md.

REDESIGN-LAYOUT2.md

@@ -191,3 +191,4 @@ Legend: ⬜ todo · 🔄 in progress · ✅ done
 - 2026-06-23 — Popups single-source: `--popup-bg` now = `var(--card-bg)` (dark); stripped 8 inline `background: var(--card-bg)` overrides on `popupSurfaceStyle` so loader/modals/menus all use the token. Light stays opaque white.
 - 2026-06-23 — Dashboard reflow: row2 = To Do (fluid) + Calendar (280px); row3 = Activity / In-Progress / Team Perf. New `.dash-row-todo` / `.dash-row-trio` classes; responsive (trio 2-up ≤1200, all stack ≤768). Retired bottomCardsHeight viewport-fill hack. Mobile-friendly is now a standing requirement for Layout2.
 - 2026-06-23 — Perf sweep: root cause = ~400–770ms/query server cold-start (compute tier, infra). Code fixes: added FK/filter index migration (pushed to DB); removed redundant client/external scope waterfall in Tasks + Dashboard (rely on RLS, verified `has_company_access`/`project_members` parity); embedded submitter-profiles + deliveries into the Tasks submissions query (−2 round trips all roles). Test client/external dashboards on 5173.
+- 2026-07-15 — Naming cleanup: the 91045a1 Project→Client rename was only partially walked back by later commits, leaving the project entity mislabeled "Client" in ~20 spots (Add Project modal, filters, PO/report/dashboard columns, etc.) while table headers already said "Project". Confirmed with user: **Company** = the customer org (e.g. "Public Storage"), **Project** = a job within that company — "Client" was a leftover label, not a third entity. Reverted all mislabeled text to "Project"; reverted the `/clients/:id` route back to canonical `/projects/:id` (nothing deployed to prod yet, so no live URLs broke). Also: removed stale pre-redesign `layout.md` (superseded by this doc), stopped tracking `.env.backfill` (had a live admin password/token committed — rotate those credentials separately).