fix(types): replace structural DB types with Pick<PrismaClient> and remove Prisma boundary as any casts

Replace ~440 lines of hand-written structural DB client types across 7 lib files
with `Pick<PrismaClient, ...>` from @capakraken/db. This eliminates all `as any`
casts at Prisma boundaries (cron routes, allocation effects, vacation procedures)
and surfaces two pre-existing bugs:
- weekly-digest.ts: `db.allocation.count()` called non-existent model (fixed → demandRequirement)
- estimate-reminders.ts: `submittedAt` field doesn't exist on EstimateVersion (fixed → updatedAt)

Also adds root eslint.config.mjs so lint-staged can lint package files.

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

eslint.config.mjs

@@ -0,0 +1,17 @@
+import baseConfig from "@capakraken/eslint-config/base";
+
+/** @type {import("eslint").Linter.FlatConfig[]} */
+export default [
+  ...baseConfig,
+  {
+    ignores: [
+      "apps/**",
+      "node_modules/**",
+      ".claude/**",
+      "backups/**",
+      "tooling/**",
+      "**/dist/**",
+      "**/build/**",
+    ],
+  },
+];