Sync: officeholders v3 — fresh export from live Atlas DB (13,329 tenures)

Re-exported directly from Postgres (10.0.0.116), not Atlas's introspection,
which under-reported the roster (its v3 export had 11,473, missing the
restored Florida League of Cities municipal set). Live DB current tenures:
state 7,561 · municipal 4,009 · county 1,217 · federal 542.

- build.py now reads officeholders-v3.jsonl (was v2); dataset vintage 2026-07-04
- fixed one corrupt start_date at source-export (21021-12-03 -> 2021-12-03,
  Lorraine Borowski, Mayor of Decorah IA)
- scripts/build_viz.py: committed, deterministic generator for the Board's
  county_data.json / county_detail.json (previously built ad-hoc)
- generate_changelog.py: ignore files whose only change is the vintage stamp,
  so the diff reflects government change, not re-export bookkeeping

Person files 11,285 -> 13,329. Non-FL municipal officials (1,903) are in the
tree but not yet county-mappable (place->county crosswalk still NULL).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

data/jurisdictions/us/states/pa/people/steve-samuelson.md

@@ -26,7 +26,7 @@ sources:
     source: "SLDL (Census 2025)"
 confidence: official
 tags: [officeholder, state, legislative, pa]
-timestamp: "2026-06-20"
+timestamp: "2026-07-04"
 ---
 
 # Steve Samuelson
@@ -38,4 +38,4 @@ Current PA House District 135 (PA State House of Representatives District 135).
 - tenure: OpenStates YAML via GitHub 2026-06-20
 - jurisdiction: SLDL (Census 2025)
 
-Generated from the Atlas officeholders v2 export (2026-06-20).
+Generated from the Atlas officeholders v3 export (2026-07-04).