Add owner-only logging and Brickset API call tracking

LIM configured no logging at all, so the instruction fetcher had no trail to follow. Adds a rotating file handler on the root logger plus two owner-only admin pages.

- Admin > Logs: filter by level, source and text; tracebacks kept with their error; auto-refresh, raw download, rotated-file browsing and rotate-now

- Admin > Logs > Brickset API calls: every outbound call recorded with method, params, caller, duration, result count and error, plus daily quota accounting (only getSets counts) and a comparison against getKeyUsageStats

- New owner concept (services/ownership.py): a single account, distinct from is_admin, since these pages expose other admins activity. Defaults to the first admin; flask owner show/set to change

- Services now log through module loggers; retention setting and pruning for call records

- New CLI: flask owner show/set, flask logs path/prune

- New table brickset_api_calls, created automatically at boot; LOG_* env vars, /data/logs in Docker

app/models/site_setting.py

@@ -32,6 +32,10 @@ DEFAULTS = {
     'fetch_skip_sets_with_pdfs': 'true',
     'fetch_allow_setid_lookup': 'true',
     'fetch_last_run': '',
+
+    # Logging / API call history
+    'owner_user_id': '',
+    'api_log_retention_days': '90',
 }
 
 VISIBILITIES = ('private', 'shared', 'public')