v1.8.0: warehouse module (16 commits), docházka mzda model, leave_type=holiday removal, api.ts race fix

Highlights:
- Warehouse module: receipts, issues, reservations, inventory, reports, dashboard,
  master data (categories, suppliers, locations), FIFO service, integration tests
- Docházka: mzda PDF counting model (Odpracováno / Vč. svátků / Přesčas / Svátek /
  So/Ne / Noc) with Czech weekday names and decimal hours
- AttendanceAdmin/AttendanceHistory KPI cards unified to mzda formula with
  fund bar colored by delta, badges for Práce/Dov/Nem/Sv/Nep
- Remove leave_type=holiday entirely (auto-computed from Czech public holidays)
- Allow multiple work shifts per day (overlap detection only)
- Pre-flight refresh in api.ts eliminates spurious 401s on fresh page loads
- Prisma: company_settings gets 6 nullable columns for warehouse numbering
  (PRI/VYD/INV prefixes, default patterns); migration seeds defaults

src/server.ts

@@ -6,6 +6,7 @@ import rateLimit from "@fastify/rate-limit";
 import path from "path";
 import { config } from "./config/env";
 import { securityHeaders } from "./middleware/security";
+import prisma from "./config/database";
 
 import authRoutes from "./routes/admin/auth";
 import usersRoutes from "./routes/admin/users";
@@ -64,10 +65,26 @@ async function start() {
   await app.register(cookie);
 
   // --- Health check (before rate-limit so monitoring isn't throttled) ---
-  app.get("/api/health", async () => ({
-    status: "ok",
-    timestamp: new Date().toISOString(),
-  }));
+  // Pings the database so load balancers / PM2 can detect a broken instance.
+  // Returns 503 with { status: "unhealthy", ... } if the DB is unreachable.
+  app.get("/api/health", async (_request, reply) => {
+    try {
+      await prisma.$queryRaw`SELECT 1`;
+    } catch (err) {
+      reply.status(503);
+      return {
+        status: "unhealthy",
+        database: "unreachable",
+        error: err instanceof Error ? err.message : "unknown",
+        timestamp: new Date().toISOString(),
+      };
+    }
+    return {
+      status: "ok",
+      database: "reachable",
+      timestamp: new Date().toISOString(),
+    };
+  });
 
   await app.register(rateLimit, {
     max: config.rateLimit.max,