feat: native multimodal file handling; openai responses api

- add input_files parameter to Crew.kickoff(), Flow.kickoff(), Task, and Agent.kickoff()
- add provider-specific file uploaders for OpenAI, Anthropic, Gemini, and Bedrock
- add file type detection, constraint validation, and automatic format conversion
- add URL file source support for multimodal content
- add streaming uploads for large files
- add prompt caching support for Anthropic
- add OpenAI Responses API support

lib/crewai/pyproject.toml

@@ -98,6 +98,9 @@ a2a = [
      "httpx-sse~=0.4.0",
      "aiocache[redis,memcached]~=0.12.3",
 ]
+file-processing = [
+    "crewai-files",
+]
 
 
 [project.scripts]
@@ -124,6 +127,7 @@ torchvision = [
   { index = "pytorch-nightly", marker = "python_version >= '3.13'" },
   { index = "pytorch", marker = "python_version < '3.13'" },
 ]
+crewai-files = { workspace = true }
 
 
 [build-system]