feat: leads capture API with PostgreSQL backend

Bun + Hono API service for capturing email subscribers across
multiple projects. Supports subscribe/unsubscribe, admin stats,
and deduplication per email+project pair.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -0,0 +1,13 @@
+{
+  "name": "leads-api",
+  "version": "0.1.0",
+  "type": "module",
+  "scripts": {
+    "start": "bun run src/index.ts",
+    "dev": "bun --watch run src/index.ts"
+  },
+  "dependencies": {
+    "hono": "^4",
+    "postgres": "^3"
+  }
+}