Make server failures debuggable without leaking secrets:
- configurable stdout log level (config.yaml logging.level + OWNCORD_LOGGING_LEVEL)
- preserve the DB cause in ErrInternal wraps; log auth-DB failures distinctly
from bad tokens; log the previously-silent expired-session cleanup goroutine
- route HTTP handler panics through slog (was chi stderr-only, invisible to
the admin log stream)
- stackutil: argument-free panic stacks so key/token bytes never reach the
admin ring buffer / SSE; slog.LogValuer redaction on VoiceConfig/GitHubConfig/
GIFConfig/Config and db.User/db.Session
- logctx: req_id/trace_id correlation on ...Context log calls
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
