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/dashboard.html

@@ -260,6 +260,13 @@
                             <i class="bi bi-cloud-arrow-down"></i> Instruction Fetcher
                         </a>
                     </div>
+                    {% if current_user_is_owner %}
+                    <div class="col-md-3 mb-2">
+                        <a href="{{ url_for('logs.index') }}" class="btn btn-outline-dark w-100">
+                            <i class="bi bi-journal-text"></i> Logs
+                        </a>
+                    </div>
+                    {% endif %}
                     <div class="col-md-3 mb-2">
                         <a href="{{ url_for('admin.users') }}" class="btn btn-outline-primary w-100">
                             <i class="bi bi-people"></i> Manage Users