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>

packages/db/package.json

@@ -0,0 +1,33 @@
+{
+  "name": "@linkder/db",
+  "version": "0.0.0",
+  "private": true,
+  "type": "module",
+  "main": "./src/index.ts",
+  "types": "./src/index.ts",
+  "exports": {
+    ".": "./src/index.ts",
+    "./schema": "./src/schema/index.ts"
+  },
+  "scripts": {
+    "generate": "drizzle-kit generate && node scripts/fix-postgis.mjs",
+    "migrate": "tsx src/migrate.ts",
+    "push": "drizzle-kit push",
+    "studio": "drizzle-kit studio",
+    "seed": "tsx src/seed.ts",
+    "typecheck": "tsc --noEmit",
+    "test": "vitest run"
+  },
+  "dependencies": {
+    "@linkder/shared": "workspace:*",
+    "drizzle-orm": "0.38.4",
+    "postgres": "^3.4.5"
+  },
+  "devDependencies": {
+    "dotenv": "^16.4.7",
+    "drizzle-kit": "^0.30.1",
+    "tsx": "^4.19.2",
+    "vitest": "^2.1.8",
+    "typescript": "^5.7.3"
+  }
+}