The validate-url-allows-public-{https,http} tests relied on real DNS
resolution of example.com, which fails in containers without public
DNS access. Mock resolve-host to return a known public IP, consistent
with the pattern used by other tests in the same file.
AI-assisted-by: mimo-v2.5-pro
Add :uri and :scheme/:host keys to exceptions raised by
`validate-uri` for better error diagnostics. Also fix a bug
where (str url) was used instead of (str uri) in the
host-missing exception path.
Update the existing blocked-target test to verify the new :uri
key, and add three new tests covering scheme rejection, missing
host, and DNS failure error paths. All 27 tests pass with 60
assertions and 0 failures.
Signed-off-by: Andrey Antukh <niwi@niwi.nz>
