`list projects` fails with "error decoding response body"

[saramaebee]

What

fossapi list projects fails with a deserialization error against the
real /api/projects endpoint:

$ fossapi list projects --json --count 1
Error: HTTP error: error decoding response body

The same key works fine for get project <locator>, get revision <locator>, and a direct curl against /api/projects?count=1 returns
valid JSON — so the response itself is well-formed. Only fossapi's
response struct is intolerant of something in it.

Suggested fix

• Make the response struct tolerant of unknown / nullable fields
  (#[serde(default)], Option<T>).
• If repro is hard to set up, comparing the live /api/projects JSON
  shape against the struct definition should surface the offending
  field(s).