OrdersResource.fills / fills_all hits /portfolio/fills — belongs on PortfolioResource #351

Problem

PortfolioResource owns the /portfolio/* family — balance, positions, settlements, deposits, withdrawals — except for fills, which sits on OrdersResource even though the URL is /portfolio/fills and the response shape (Page[Fill] with cursor + min_ts/max_ts/ticker filters) matches settlements() exactly.

A user discovering the SDK via autocomplete on client.portfolio. will not find their fills and may infer the endpoint doesn't exist. The grouping also breaks the README's framing of portfolio.deposits() / portfolio.withdrawals() as the cost-introspection family.

Evidence

• kalshi/resources/orders.py:584-608 — fills lives on OrdersResource and hits /portfolio/fills

def fills(self, *, ticker: str | None = None, ...) -> Page[Fill]:
    ...
    return self._list(
        "/portfolio/fills", Fill, "fills", params=params, extra_headers=extra_headers
    )

• kalshi/resources/portfolio.py:144,220,254 — settlements, deposits, withdrawals all live on PortfolioResource with identical Page[T] shape.

Suggested fix

Add fills / fills_all to PortfolioResource (and AsyncPortfolioResource) with the same signatures. Leave a one-version forwarding shim on OrdersResource.fills / fills_all that emits DeprecationWarning and delegates to the new location. Update docs/resources/orders.md and docs/resources/portfolio.md to reflect the migration, and add a test that asserts both spellings resolve during the transition.

Source

Round-3 independent audit (reviewer: resources_api).