`FrameProcessorSetup.pipeline_task` is now mandatory and
`FrameProcessor.pipeline_task` raises if accessed before setup
instead of returning `None`. `FunctionCallParams` gains a
required `pipeline_task` field and `LLMService._run_function_call`
populates it (plus reads `app_resources` directly off the
pipeline task). Tests that build a processor or
`FunctionCallParams` outside a real pipeline stub it with a
`SimpleNamespace`.
