Gallery pages embed warning/stderr blocks from example execution #19

Most gallery pages (01–09) render a captured stderr block above their figures — tech-mapping fuzzy-match warnings, missing-dataset warnings, etc., complete with build-machine file paths (CI runner paths in the deployed docs). It's noise that makes polished examples look broken.

Two-level fix:

1. Cosmetic: examples silence expected warnings (the new example 10 does this deliberately for the fixture's missing-storage warnings) or sphinx-gallery is configured to not capture stderr.
2. Root cause: some of these warnings are telling us something (e.g. technologies missing from standard mappings for the fixture) — fixing the fixture's palette/mapping coverage removes the warning honestly instead of hiding it.

Related: #14 (gallery rendering defects) — same audit pass could cover both.

Also noted while building: MultiScenario's pass-through getters (get_area_dispatch() etc.) accept no kwargs, so per-scenario options like include_charging=False can't be forwarded — a small API gap worth fixing alongside.