feat: add randomize to @func_latency_control

[Aj33tSKY]

Summary

Adds randomize to @func_latency_control so ADK projects can opt into shuffling delay responses per call.

Changes

• @func_latency_control(..., randomize: bool = False)
• Parse/render/to_proto/create wiring on FunctionLatencyControl
• Updated functions_pb2 bindings
• Docs + unit tests

Test strategy

• Added/updated unit tests
• Manual CLI testing (poly <command>)
• Tested against a live Agent Studio project
• N/A (docs, config, or trivial change)

Checklist

• ruff check . and ruff format --check . pass
• pytest passes (latency/randomize cases)
• No breaking changes to the poly CLI interface (or migration path documented)
• Commit messages follow conventional commits

Example

@func_latency_control(
    delay_before_responses_start=0,
    silence_after_each_response=2,
    delay_responses=[("$delay_1", 3), ("$delay_2", 2)],
    randomize=True,
)

[github-actions]

Coverage Report

Base (main)	PR	Change
72.7%	72.7%	+0.0% ✅

Changed file coverage

File	Coverage	Change
poly/resources/function.py	81.3%	+0.9% ✅