Update OKF docs bundle, README, and CLAUDE.md for today's features

Documents the shift planning and closure/payroll modules (new tables,
routes, stores), the dark redesign, and the docker-compose-broken-host
workaround. Adds CLAUDE.md pointing agents at docs/. Translates README to
English and keeps host-specific infrastructure details out of the repo.

docs/api/shifts-routes.md

@@ -0,0 +1,48 @@
+---
+type: API Endpoint
+title: Shift planning routes (employee)
+description: GET /api/shifts/available, GET /api/shifts/mine, POST/DELETE /api/shifts/:slotId/signup.
+resource: backend/src/routes/shifts.ts
+tags: [api, shift-planning]
+timestamp: 2026-08-16T00:00:00Z
+---
+
+# Shift planning routes (employee)
+
+Mounted at `/api/shifts`. Every route requires `requireAuth` +
+`requireEmployee`.
+
+# Examples
+
+```
+GET /api/shifts/available?period=YYYY-MM
+200 -> { "slots": AvailableSlot[] }
+```
+Open slots the employee isn't already signed up for. `period` defaults to
+the current month if omitted/invalid. Also the trigger point for lazily
+generating that month's template — see
+[shift_slots](/docs/data-model/shift-slots.md).
+
+```
+GET /api/shifts/mine?period=YYYY-MM
+200 -> { "slots": MySlot[] }
+```
+
+```
+POST /api/shifts/:slotId/signup
+201 -> { "ok": true }
+400 -> collision with another approved slot, already full, already signed
+       up, or the slot is closed — see [shift_signups](/docs/data-model/shift-signups.md)
+```
+
+```
+DELETE /api/shifts/:slotId/signup
+204 on success
+400 -> not signed up for that slot
+```
+
+# Related
+
+- [shift_slots](/docs/data-model/shift-slots.md), [shift_signups](/docs/data-model/shift-signups.md)
+- [Admin routes](./admin-routes.md) — the admin-side calendar, manual assignment, and month generation
+- [Frontend stores](/docs/frontend/stores.md) — `shiftPlanningStore`