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/clay/index.md

@@ -32,7 +32,7 @@ timestamp: "2026-07-03"
 
 # Clay County, IA
 
-County jurisdiction.
+County jurisdiction — 2 officeholders mapped.
 
 ## Demographics (ACS 2023)
 

data/jurisdictions/us/states/ia/counties/clay/municipalities/everly/people/ron-thompson.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Ron Thompson"
+description: "Mayor, Everly, IA"
+role: "Mayor, Everly, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "e7f3105e-bea9-44ec-8fb5-a0d090b7c2eb"
+  office: "9fce2792-aefe-4c7a-90b6-351d4d58ca79"
+  tenure: "bdf85066-e908-4803-97c8-bdfb28c60e79"
+  jurisdiction: "916e803e-86a5-4772-a051-cc5a6bb6708e"
+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"
+---
+
+# Ron Thompson
+
+Current Mayor, Everly, 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/clay/municipalities/spencer/people/steve-bomgaars.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Steve Bomgaars"
+description: "Mayor, Spencer, IA"
+role: "Mayor, Spencer, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2022-01-01"
+  current: true
+ids:
+  person: "31c9e5a1-0cc3-46f2-b64c-662db91d0ccd"
+  office: "6468ff84-d8ad-4191-aaa8-6ff2987822ee"
+  tenure: "681fccff-9250-4fac-84fe-b67ffd13a996"
+  jurisdiction: "daf1cbf1-77ea-4429-a697-c1a29e836dca"
+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"
+---
+
+# Steve Bomgaars
+
+Current Mayor, Spencer, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).