allow custom handlers and prompts in functions

[zzstoatzz]

closes #1124 (see this example)

also see new examples

• custom handler to show whatever you want in the console
• custom prompts to add onto or replace the default prompts for the high level utils

[Copilot]

Pull Request Overview

This PR enables the use of custom handlers and prompts in functions while modernizing type annotations and agent interactions across several examples. Key changes include:

• Adding type annotations and inline type ignores where needed (e.g. in record_audio).
• Introducing a new custom handler (ShowPromptHandler) and updating agent tool configurations.
• Replacing legacy agent tool examples with updated asynchronous implementations and prompt string adjustments.

Reviewed Changes

Copilot reviewed 23 out of 33 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
examples/talk_to_marvin.py	Added type annotations to record_audio and updated the pyaudio import comment.
examples/slackbot/search.py	Added explicit type annotation for the results variable.
examples/provider_specific/openai/run_agent.py	Updated the agent initialization with provider-based API configuration.
examples/hello_task.py	Updated the task instantiation with a generic type parameter.
examples/hello_fn.py	Updated the function decorator to include a prompt argument.
examples/hello_agent.py	Refactored the file functions and adjusted the agent’s prompt string.
examples/deepseek_chat.py	Switched to asynchronous agent execution using run_async.
examples/custom_handler.py	Added a custom handler that prints the initial user prompt.
examples/agent_uses_tools.py	Removed redundant agent tool usage in favor of updated implementations.

Files not reviewed (10)

• .cursor/rules/python-style.mdc: Language not supported
• docs/api-reference/marvin-agents-agent.mdx: Language not supported
• docs/api-reference/marvin-fns-cast.mdx: Language not supported
• docs/api-reference/marvin-fns-classify.mdx: Language not supported
• docs/api-reference/marvin-fns-extract.mdx: Language not supported
• docs/api-reference/marvin-fns-fn.mdx: Language not supported
• docs/api-reference/marvin-fns-generate.mdx: Language not supported
• docs/api-reference/marvin-fns-say.mdx: Language not supported
• docs/api-reference/marvin-fns-summarize.mdx: Language not supported
• docs/api-reference/marvin-handlers-queue_handler.mdx: Language not supported