refactor: migrate to audio_downloader package, fix promo to Spots, filter NW date files, add --download-promo

[wardbryan3]

Summary

Reorganize the project into a proper audio_downloader Python package, fix promo file handling across multiple sources, and add CLI improvements for promo downloads.

Changes

Package Reorganization (10 commits)

• Move all source files (main.py, config.py, gui.py, browser_manager.py, constants.py, download_utils.py, sources/) into audio_downloader/ package
• Add pyproject.toml with setuptools build config and audio_downloader/__main__.py for python -m audio_downloader entry point
• Update all internal imports to use audio_downloader. prefix, removing sys.path.insert(0,...) workarounds
• Move test scripts to tests/ and Windows batch files to scripts/ for cleaner project root
• Update PyInstaller spec (AudioDownloader.spec) with new package paths and hidden imports
• Update .github/workflows/windows_build.yml for new file locations
• Update AGENTS.md with new project structure and developer commands

Promo File Handling Fixes

• WITC promos now go to Spots/ directory instead of staying in the global features output directory. Promos are moved to Spots/WITC_PROMO_MM-DD-YY.mp3 with dated filenames.
• NW Outdoors date-stamped files filtered: Files matching NWoutdoors<6digits>.mp3 are now skipped after ZIP extraction, preventing stale date-stamped content from being copied into the global features folder.
• NW Outdoors promo labeling consistency: Progress messages and class docstrings updated from "Global Features" to "GLOBAL FEATURES".
• GUI button text updated from "Download Global Features" to "Download GLOBAL FEATURES".

Config & Path Changes

• Add get_spots_dir() to ConfigManager — creates and manages a Spots/ subdirectory under the output base
• Add Spots/ to ensure_folders() and validate_config() checks
• Rename "Global Features" reference path to "GLOBAL FEATURES" (uppercase) for consistency with actual folder naming
• .gitignore: add docs/superpowers/ to ignore AI design docs

CLI Improvements

• Add --download-promo flag and run_promo_download() function for downloading the Northwest Outdoors promo standalone via CLI
• Add python -m audio_downloader --download-promo as a supported invocation
• Update batch scripts (scripts/download_global_features.bat, scripts/download_promos.bat) to use correct working directory (%~dp0.. instead of %~dp0)

Documentation

• Add scripts/witc_promo_rename.bat — PowerShell-based WITC promo renaming script that finds the upcoming Saturday's promo and copies it to WITC_PROMO.mp3
• Add weekly automation design spec at docs/superpowers/specs/2026-06-26-weekly-automation-design.md covering the future consolidated weekly download pipeline

Testing

• Update all test files for package restructuring (audio_downloader. prefix, new module paths)
• Update test imports and mock patches to use audio_downloader. package references
• Update WITC tests (test_weekend_in_the_country.py) to verify promos are moved to Spots/ directory instead of staying in-place — all 8 tests pass
• Add test_northwest_outdoors_date_stamped_file_filter to test_sources.py — verifies the regex pattern for filtering NWoutdoors<6digits>.mp3 files
• Remove sys.path.insert(0,...) hacks from test files, using proper package imports instead

Test Plan

.venv/bin/python tests/test_sources.py
.venv/bin/python tests/test_weekend_in_the_country.py
.venv/bin/python tests/test_config_edge_cases.py
.venv/bin/python tests/test_download_utils.py
.venv/bin/python tests/test_browser_manager.py
.venv/bin/python tests/test_integration.py