Fix microphone config path handling

[tinyopsstudio]

Fixes #7
/claim #7

Summary:

• load microphone config from the repository root mic_config.json by default instead of config\mic_config.json
• allow BONZI_MIC_CONFIG to override the config path for tests or custom installs
• create the config parent directory when saving and lazy-load pyaudio so config load/save can be tested without audio hardware bindings
• add stdlib unittest coverage for missing config and save/load round trip

Why:

• the repo ships mic_config.json in the project root, but helpers/mic.py looked for a Windows-style config\mic_config.json path and emitted a Python invalid escape warning
• first-run microphone setup could fail when trying to save into a missing config directory

Verification:

• python3 -m unittest discover -s tests
• python3 -m py_compile main.py helpers/*.py tests/*.py
• git diff --check

No private credentials, tokens, or local config values are included.

[opirebot]

👀 We've notified the reward creators here.
Make sure your payment account is ready to receive the payment for your hard work 💪

[tinyopsstudio]

Hi, quick follow-up on this PR. The patch remains focused on the microphone config path and includes the unittest, py_compile, and diff-check verification in the PR body. I am happy to adjust it if you prefer one of the competing approaches; if another PR is preferred, a close or decline signal would also help keep the Opire claim state accurate. Thanks.