WP-00: application foundation

Scaffolds the project: Next.js 16 App Router with strict TypeScript,
Prisma 7 on PostgreSQL 16, Tailwind 4, Vitest, Playwright, CI, and a
standalone Docker image that applies migrations on boot.

Makes the no-tracker rule of PLAN.md 3.7 enforceable rather than
stated. A per-request nonce-based CSP names no external origin, a unit
test fails if any network directive gains one, and a second test fails
if a tracking package appears in package.json. The end-to-end test
drives the standalone server the Docker image runs, not `next dev`,
so a proxy matcher that stopped matching could not pass unnoticed.

Environment is validated at import, so a missing DATABASE_URL fails at
boot with a readable message instead of surfacing later as a driver
error mid-export. ENCRYPTION_KEY is checked to be 32 bytes.

Three deviations from the plan, recorded in PLAN.md and README:
Next 16 rather than 15, `proxy.ts` rather than the now-deprecated
`middleware.ts`, and database-backed sessions rather than Auth.js v5,
which is still beta and whose JWTs would make the session revocation
required by compliance item 23 awkward.

Verified locally against PostgreSQL 16: migrations apply, extensions
created, typecheck, lint, 9 unit tests and the end-to-end header test
all pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Cr9dkEHwbDgkWPnyGj1Rjv

.gitignore

@@ -0,0 +1,23 @@
+node_modules/
+.pnpm-store/
+
+.next/
+out/
+build/
+next-env.d.ts
+*.tsbuildinfo
+
+.env
+.env.*
+!.env.example
+
+coverage/
+test-results/
+playwright-report/
+blob-report/
+.playwright/
+
+.DS_Store
+*.log
+.tmp/
+.pgdata/