Documentation Build Warning Handler

Problem Description

A developer tools company ships a CLI that generates HTML documentation from Python docstrings. Their build pipeline uses a popular documentation generator that has recently started emitting deprecation warnings about an old configuration key — the warnings appear in stderr but the documentation output is always correct and complete. These warnings are cluttering the CI logs and the team wants to handle them systematically.

The team also anticipates they'll need to handle other minor build warnings in the future (e.g., missing optional metadata fields, non-fatal rendering hints). They want a Python module that categorizes and handles these low-severity warnings in a consistent way, with a clear policy on when to keep retrying the build step vs. when to just log and move on.

Output Specification

Write a Python module build_warning_handler.py that:

• Handles low-severity warnings that do not affect output correctness
• Implements a retry policy appropriate for this type of failure
• Includes a WarningReport dataclass or similar result structure capturing what happened
• Includes a short POLICY.md explaining the retry/log strategy used

The module should be importable without any external dependencies beyond the standard library.