feat(stock): add inventory module with lot/serial tracking

[jay009id]

Summary

Adds a new stock inventory module along with lot/serial tracking for products and supporting account & menu changes.

Changes

✨ feat(stock) — new module

• Inventory transfers, moves, and quants management
• Stock lots with reordering rules
• Warehouse and scrap views (form & list)

✨ feat(product)

• Lot/serial number tracking
• Automotive demo catalog

🔧 fix(account)

• Mark name fields unique to support module data sync upserts

✨ feat(menus)

• Add web_icon to account & product menu items

Scope

Module	Files
stock	51 (new)
account	12
product	6

Total: 69 files changed, +3,802 −71

Notes

• No migrations impact beyond new module data.
• Ready for review against dev.