spatial_filter, org_type parameters silently ignore invalid values

## Description
Passing invalid values to `spatial_filter` or `org_type` on `/search` returns HTTP 200 with unfiltered or empty results rather than a validation error.

## Steps to Reproduce
GET https://catalog.data.gov/search?spatial_filter=badvalue
GET https://catalog.data.gov/search?org_type=FakeType

## Expected Behavior
HTTP 422 -- both parameters have a fixed set of valid values defined in the OpenAPI spec.

## Actual Behavior
- `spatial_filter=badvalue` returns HTTP 200 with unfiltered results as if the parameter was not provided
- `org_type=FakeType` returns HTTP 200 with zero results -- indistinguishable from a valid org type with no matching datasets

## Notes
Confirmed April 27, 2026. May be intentional permissive behavior -- need to confirm. If intentional, at minimum the docs should note that invalid values are silently ignored.