modernization: SQLite WAL, subprocess.run, TODO.md
- db/sqlite.py: enable WAL journal mode per connection — concurrent
readers no longer block writers
- Replace subprocess.call() with subprocess.run() in 8 files
(output.py, qa.py, tools.py, client/misc.py, client/interfaces/db.py,
portage_plugin, solo/conf.py)
- Replace os.popen() with subprocess.run() in tools.py and
core/settings/base.py
- Add TODO.md documenting deferred logging module integration
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>