Import position inception and dissolved dates from Wikidata

Wikidata has temporal data on position entities that tells us when a position was created and when it was abolished:

• P571 (inception) — when the position was established
• P576 (dissolved/abolished) — when the position ceased to exist

For example, "Member of the House of Lords of Great Britain" (Q110314996) has P571: 1707 and P576: 1800. Without this data, we can suggest historically invalid positions during enrichment.

What to do

1. Add inception and dissolved date columns to the positions table
2. Extract P571/P576 from the Wikidata dump during position import
3. Use dissolved dates during enrichment to avoid mapping to abolished positions

Start by locating the positions table, the Wikidata position-import path, and the enrichment logic. Trace how position properties are extracted and how candidates are mapped; done means P571/P576 populate the new columns and enrichment avoids positions abolished before the relevant date.