## Summary
This finishes the org credit line workflow so it behaves like reserved treasury-backed credit instead of a simple member allowance.
## What changed
- reserve org funds immediately when a credit line is assigned
- track credit lines with:
- approved amount
- available amount
- outstanding principal
- interest rate
- amount due
- consume reserved credit during store checkout without charging org funds a second time
- add credit line repayment through the bank app
- sync richer credit line state into org and bank payloads/UI
- keep legacy `amount` compatibility mapped to available credit for older consumers
## User-facing behavior
- assigning a credit line now reduces available org funds immediately
- spending on `credit_line` reduces available credit and creates debt with interest
- the bank app now shows outstanding credit debt and allows repayment from personal bank funds
- the org treasury view now shows reserved credit and outstanding due totals
## Validation
- `cargo fmt`
- `npm run build:webui`
- `cargo test -p forge-services --quiet`
- `cargo test -p forge-server --quiet`
## Follow-up checks
- validate in-game that assigning a credit line reduces org funds immediately
- validate store checkout with `credit_line` updates available credit and debt correctly
- validate bank repayment decreases player bank balance, increases org funds, and reduces amount due
Co-authored-by: Jacob Schmidt <innovativestudios@outlook.com>
Reviewed-on: #2
