Warn and ignore typical_p on API requests instead of rejecting them - #18551

Fixes #18542.

PR #18448 made scheduleRunner reject any generate/chat request that carries typical_p with a 400 ("typical_p is no longer supported"). That breaks existing clients that cannot omit the parameter: e.g. SillyTavern always sends typical_p (set to the no-op value 1.0), so upgrading to 0.34.1 makes all its generations fail even though the client is not trying to use typical-p sampling.

Change: scheduleRunner now logs a warning and drops typical_p from the request options instead of failing the request. Model-level typical_p values stored in existing models are still honored through the model options path, and the ollama create / PARAMETER typical_p rejection is unchanged (that is a deliberate user action where a hard error is appropriate).

Tests:

• Updated TestGenerate/ignored_deprecated_option (was rejected option): a generate request with Options: {"typical_p": 0.5} now returns 200 instead of 400.
• go vet ./server/ clean; go test ./server/ -run TestGenerate passes (including the updated subtest and the adjacent null option is unset case). Full ./server suite has one pre-existing failure (TestPullManifestRedirectPolicy) which also fails on the unmodified tree.