Fix API build: shared package emits dist, fix type errors

- packages/shared: tsconfig adds outDir/declaration, package.json adds build script
- apps/api/tsconfig.json: paths now point to shared/dist (.d.ts) instead of source,
  resolves TS6059 rootDir conflict
- apps/api/src/routes/{health,notifications,users}.ts: explicit Router type annotation
  to fix TS2742 portable type inference
- apps/api/src/events/handler.ts: cast via 'as unknown as' to satisfy TS2352
- apps/api/Dockerfile: build shared package before api

apps/api/src/routes/users.ts

@@ -1,8 +1,8 @@
-import { Router, type Request, type Response, type NextFunction } from 'express';
+import { Router, type Request, type Response, type NextFunction, type Router as ExpressRouter } from 'express';
 import { supabaseAdmin } from '../lib/supabase.js';
 import type { UserRole } from '@naturcalabacera/shared';
 
-const router = Router();
+const router: ExpressRouter = Router();
 
 const VALID_ROLES: UserRole[] = ['admin', 'internal_staff', 'external_availability_viewer'];