feat: task 1.3 vite dev proxy + tsconfig hardening

Same-origin dev proxy via Vite's server.proxy:
- /api/*       -> ${VITE_DEV_DIRECTUS_URL}/*   (Directus REST + GraphQL)
- /ws-business -> ws://.../websocket           (Directus business-plane WS)
- /ws-live     -> ${VITE_DEV_PROCESSOR_WS_URL} (Processor live WS, Phase 1.5)

WS proxy targets derive ws:// scheme from the http(s) Directus URL.
loadEnv reads VITE_DEV_* overrides; sensible localhost defaults.

tsconfig.app.json: noUncheckedIndexedAccess + noImplicitOverride.

.env.example documents the two override vars; .env.local is gitignored
via the existing *.local pattern.

README "Local dev" section: proxy table + override instructions + port
collision workaround.

Deviation: spec called for .env.dev.example/.env.dev.local but Vite's
dev mode is "development" not "dev", so mode-specific files would be
.env.development.* and Vite wouldn't auto-load .env.dev.local. Switched
to the standard Vite .env.example/.env.local convention. Documented in
the task's Done section.

Plus: backfill 1.2 commit SHA (9918418) in its Done section.

.planning/phase-1-foundation/02-stack-rounding-out.md

@@ -107,4 +107,4 @@ Stack rounded out: Tailwind 4 via `@tailwindcss/vite`, shadcn/ui (slate base / n
 
 **Smoke check:** `pnpm typecheck`, `pnpm lint`, `pnpm format:check`, `pnpm build` all green. `App.tsx` renders a Tailwind-styled centered card with a shadcn `Button` to prove the toolchain works end-to-end. Bundle: 222KB raw / 70KB gzipped.
 
-(Commit SHA pending — work landed locally, not yet committed.)
+Landed in `9918418`.