feat(multimodal): add uuid-based caching optimization for media processing

introduce uuid fields in multimodal data structures to enable efficient cache lookups and bypass expensive media fetching and processing when possible. this optimization reduces redundant operations by leveraging user-provided uuids for images, videos, and audio content.

- add `uuid` field to chat utils param types
- implement cache key extraction and url-only hashing in multimodal hasher
- extend multimodal inputs with uuid fields for caching hints
- enhance processor to handle uuid-only references and reconstruct inputs from cache
- update media connector with cache-aware fetch methods to skip processing on cache hits

this change improves performance for repeated media inputs by avoiding redundant downloads and decoding.

rmv

mypy

add and discard

update flags

fix

Author: vincentzed