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/templates/admin/settings.html

@@ -11,6 +11,11 @@
         <a href="{{ url_for('instruction_fetch.index') }}" class="btn btn-outline-warning me-2">
             <i class="bi bi-cloud-arrow-down"></i> Instruction Fetcher
         </a>
+        {% if current_user_is_owner %}
+        <a href="{{ url_for('logs.index') }}" class="btn btn-outline-dark me-2">
+            <i class="bi bi-journal-text"></i> Logs
+        </a>
+        {% endif %}
         <a href="{{ url_for('backup.index') }}" class="btn btn-outline-danger me-2">
             <i class="bi bi-archive"></i> Backup &amp; Restore
         </a>