Add Restocking tab with budget-driven recommendations

[rbreitz]

Summary

• New Restocking tab: budget slider drives recommendations from inventory + demand forecasts, with a Place Order button that submits an in-memory order.
• Orders tab gains a Submitted Restocking Orders section showing order number, items, lead time, and expected delivery.
• New architecture.html overview of the system, tech stack, and data flow.
• CLAUDE.md: added code-style rule to document non-obvious logic with comments.

Commits

1. Add code style rule: document non-obvious logic with comments
2. Add architecture overview page
3. Add restocking backend: recommendations, submit, submitted list
4. Add restocking frontend: budget-driven recommendations and submission

How it works

Backend — three new endpoints in server/main.py:

• GET /api/restocking/recommendations?budget=N — priority 1: items where quantity_on_hand < reorder_point (qty = 2 * reorder_point - on_hand); priority 2: items with demand trend = increasing (qty = forecasted_demand * 0.3). Greedy-fills within the budget. Items are matched between inventory and demand forecasts by name (case-insensitive) because the two JSON files use different SKU schemes.
• POST /api/restocking/submit — stores order in submitted_orders (in-memory list in server/mock_data.py, resets on backend restart). Computes expected_delivery from the max per-category lead time (Circuit Boards 14d, Sensors 7d, Actuators 10d, Controllers 12d, Power Supplies 9d).
• GET /api/restocking/submitted — returns submitted orders, newest first.

Frontend — new client/src/views/Restocking.vue: $0–$100K budget slider, 300ms debounce, 3 summary cards (items / total cost / budget remaining), recommendations table with Below-reorder / Trend-up badges, then Place Order → success card with order number, expected delivery, and lead time. Orders.vue gains a "Submitted Restocking Orders" section above All Orders.

Test plan

• Backend: start server/ (uv run python main.py), hit GET /api/restocking/recommendations?budget=100000 — expect 4 items (TMP-201, PSU-508, SRV-301, SRV-302) totaling ~$86,525.
• Backend: POST /api/restocking/submit with the recommendations — expect RST-YYYYMMDD-HHMMSS order number, expected_delivery = today + max line-item lead time.
• Backend: GET /api/restocking/submitted returns the submitted order.
• Frontend: /restocking page loads, slider changes update recommendations (debounced), Place Order shows success card.
• Frontend: /orders shows "Submitted Restocking Orders" section with the order; section is hidden when there are no submitted orders.
• Restart backend, refresh /orders — submitted list resets (in-memory only, expected for the demo).