Municipals: nest 1,823 city officeholders under their real counties

Pull Atlas's place→county crosswalk (Census TIGER 2024 places × county
geometries, 32,041 places) into the build as a committed raw input, and
use it to resolve municipal officeholders whose county was unknown.

- data/place_county_crosswalk.jsonl — new raw input (place_geoid → county_geoid)
- build.py — place-name+state → county_geoid → ACS county slug as a fallback
  in county_slug(); city_slug() generalized to non-FL bare place labels
- data/sources/sources.yaml — provenance entry for the crosswalk

_unresolved municipals: 1919 → 58. The remainder are genuine: CT planning
regions (post-county), county-level rows mislabeled municipal upstream,
consolidated city-counties (null label), Wikidata-QID placeholder names,
and ambiguous same-name places — left unresolved rather than guessed.

Join key is county_geoid (5-digit FIPS); the directory slug is taken from
the ACS county node so municipals nest under the exact existing county dir.
Deterministic (byte-identical rebuild); validate.py passes 19,721 records.

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

data/jurisdictions/us/states/ia/counties/poweshiek/index.md

@@ -32,7 +32,7 @@ timestamp: "2026-07-03"
 
 # Poweshiek County, IA
 
-County jurisdiction.
+County jurisdiction — 3 officeholders mapped.
 
 ## Demographics (ACS 2023)
 

data/jurisdictions/us/states/ia/counties/poweshiek/municipalities/brooklyn/people/les-taylor.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Les Taylor"
+description: "Mayor, Brooklyn, IA"
+role: "Mayor, Brooklyn, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2022-01-01"
+  current: true
+ids:
+  person: "ceb2f37c-11c0-41d0-b1a9-0eaae6d9794e"
+  office: "5ac734ef-4059-49ea-8263-d4d85f2f4e9c"
+  tenure: "4048dbbd-5946-4174-a270-49c577bd4078"
+  jurisdiction: "9b76efba-b2fe-481a-bbde-4145530b71bf"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, ia]
+timestamp: "2026-07-04"
+---
+
+# Les Taylor
+
+Current Mayor, Brooklyn, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/ia/counties/poweshiek/municipalities/grinnell/people/dan-f-agnew.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Dan F. Agnew"
+description: "Mayor, Grinnell, IA"
+role: "Mayor, Grinnell, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "d8fc14e4-384b-4ce8-a29a-6419d5e7d54d"
+  office: "865f8b7b-d952-4d61-95ef-352071578069"
+  tenure: "0fcad367-fc7f-41c9-96ed-1f4e43f84d24"
+  jurisdiction: "8b3cf1da-7c19-4d5c-8f23-e17bf76b408c"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, ia]
+timestamp: "2026-07-04"
+---
+
+# Dan F. Agnew
+
+Current Mayor, Grinnell, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/ia/counties/poweshiek/municipalities/montezuma/people/colin-watts.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Colin Watts"
+description: "Mayor, Montezuma, IA"
+role: "Mayor, Montezuma, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "161d68a8-c8c3-4aeb-bcec-0c43673d8f3c"
+  office: "c5c9390f-e248-469e-8eb4-985813122929"
+  tenure: "915f3f1f-08be-4749-8bd7-28f4c3c56543"
+  jurisdiction: "8fb9241b-6525-4e89-bfb6-43d3dbed7f47"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, ia]
+timestamp: "2026-07-04"
+---
+
+# Colin Watts
+
+Current Mayor, Montezuma, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).