feat(api): Add project residency and usage quantity_unit fields (#2461)

## Summary

Add optional typed residency support to project models and project
creation, while retaining the existing optional nullable geography
inputs for both creation and update. Geography is deprecated, with its
original descriptions preserved and migration guidance appended. Add
optional quantity_unit fields to organization usage cost results,
including known units and unknown string values.

## Changes

- Add the residency configuration enum to Project and
ProjectCreateParams; residency remains a create-time input, not a new
update parameter.
- Preserve geography?: string | null on ProjectCreateParams and
ProjectUpdateParams, marked deprecated. Existing callers can continue
using geography; creation must not supply both geography and residency.
- Add optional quantity_unit fields to cost results carried by the usage
response types.

Project responses and project-creation inputs now reuse a shared
residency model. Usage cost responses reuse a shared quantity-unit
model, with unknown unit values and optional/null fields preserved.

Co-authored-by: apcha-oai <228803254+apcha-oai@users.noreply.github.com>