Add scan_log_directories() to discover.py that recursively walks
/var/log and /opt, filters to readable log files, and scores each
candidate by recency (mtime, 0.7 weight), file size (0.3), and
keyword match against an optional problem-context query (shifts
weights to 0.4/0.2/0.4 when a query is provided).
- GET /api/setup/scan?query=...&max_results=N — new API endpoint
- SourcesView: "Scan" button opens a panel with ranked candidates,
checkboxes, and "Add selected" to write to sources.yaml
- 13 new unit tests, 466 passing total
Closes: #23
