M0: foundation — monorepo, PostGIS schema, deck query, app shell

Greenfield scaffold for Linkder, a swipe-to-hire marketplace for local
professional services.

- pnpm/turbo monorepo: apps/web, packages/{shared,db}
- Postgres 16 + PostGIS via docker compose (ports 5442/6389 to avoid
  clashing with other local stacks)
- Drizzle schema, 23 tables, geography(Point,4326) with GiST indexes
- Domain core in packages/shared: integer-cent money, status transition
  graphs, deck ranking weights, cancellation policy — 46 unit tests
- Deck query: filtering in Postgres on the GiST index, ranking in JS so
  the weights stay tunable — 18 integration tests against a seeded DB
- Deterministic seed placing pros at known distances, including three
  that must NOT appear on a deck (out of radius, unverified, away)
- Next.js 15 app shell with a working swipe deck
- CI: typecheck, lint, test, build against live postgres+redis

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.env.example

@@ -0,0 +1,49 @@
+# ---- Core ----
+NODE_ENV=development
+NEXT_PUBLIC_APP_URL=http://localhost:3000
+
+# ---- Database (Postgres 16 + PostGIS) ----
+DATABASE_URL=postgresql://linkder:linkder@localhost:5442/linkder
+
+# ---- Redis (pub/sub for SSE chat + BullMQ queues) ----
+REDIS_URL=redis://localhost:6389
+
+# ---- Auth.js v5 ----
+# generate with: openssl rand -base64 32
+AUTH_SECRET=
+AUTH_URL=http://localhost:3000
+AUTH_GOOGLE_ID=
+AUTH_GOOGLE_SECRET=
+
+# ---- Phone OTP (Twilio Verify) ----
+TWILIO_ACCOUNT_SID=
+TWILIO_AUTH_TOKEN=
+TWILIO_VERIFY_SERVICE_SID=
+
+# ---- Stripe Connect ----
+STRIPE_SECRET_KEY=
+STRIPE_WEBHOOK_SECRET=
+NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY=
+# Platform commission in basis points (1500 = 15%)
+PLATFORM_FEE_BPS=1500
+
+# ---- Didit (ID verification) ----
+DIDIT_API_KEY=
+DIDIT_WORKFLOW_ID=
+DIDIT_WEBHOOK_SECRET=
+
+# ---- Cloudflare R2 (S3-compatible object storage) ----
+R2_ACCOUNT_ID=
+R2_ACCESS_KEY_ID=
+R2_SECRET_ACCESS_KEY=
+R2_BUCKET=linkder-uploads
+R2_PUBLIC_URL=
+
+# ---- Resend (transactional email) ----
+RESEND_API_KEY=
+EMAIL_FROM=noreply@linkder.app
+
+# ---- Launch market (city-scoped MVP) ----
+NEXT_PUBLIC_CITY_NAME=Barcelona
+NEXT_PUBLIC_CITY_LAT=41.3874
+NEXT_PUBLIC_CITY_LNG=2.1686