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>

docker-compose.yml

@@ -0,0 +1,35 @@
+services:
+  postgres:
+    image: postgis/postgis:16-3.4
+    restart: unless-stopped
+    environment:
+      POSTGRES_USER: linkder
+      POSTGRES_PASSWORD: linkder
+      POSTGRES_DB: linkder
+    ports:
+      - '5442:5432'
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    healthcheck:
+      test: ['CMD-SHELL', 'pg_isready -U linkder -d linkder']
+      interval: 5s
+      timeout: 5s
+      retries: 10
+
+  redis:
+    image: redis:7-alpine
+    restart: unless-stopped
+    command: redis-server --appendonly yes
+    ports:
+      - '6389:6379'
+    volumes:
+      - redisdata:/data
+    healthcheck:
+      test: ['CMD', 'redis-cli', 'ping']
+      interval: 5s
+      timeout: 3s
+      retries: 10
+
+volumes:
+  pgdata:
+  redisdata: