Switch base search_by_quarter from thematicSearchId=1 to thematic=1
(includes ZOUIT in features). Add optional category_id param that routes
ZOUIT (36940/469039/469040/469042) -> thematicSearchId=5,
ENK (39663) -> thematicSearchId=15.
Add Phase 1.5 in harvest_quarter: for each PER_CATEGORY_PROBE_CATS
category present in meta_counts (meta_total>0), run dedicated
per-category search call. Skips if category in GRID_WALK_CATS and
bbox is valid (grid-walk gives better coverage).
Curl-probe confirmed NSPD API caps at 20/category with no pagination;
categoryId param is server-ignored; thematic=1 strictly better than
thematicSearchId=1 (includes ZOUIT).
Closes part of #168 (ZOUIT/ENK coverage gap).
