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/ida/index.md

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

data/jurisdictions/us/states/ia/counties/ida/municipalities/battle-creek/people/charles-pierce.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Charles Pierce"
+description: "Mayor, Battle Creek, IA"
+role: "Mayor, Battle Creek, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "0ad7beec-9b7b-4e4a-aa56-003c25410e13"
+  office: "d783585d-59f4-411f-91d0-04e0c3d4c77c"
+  tenure: "5f93ce89-771a-4af5-9e15-2b3c3425db67"
+  jurisdiction: "ac195571-2ee2-4d15-8f0b-a5422c9655ef"
+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"
+---
+
+# Charles Pierce
+
+Current Mayor, Battle Creek, 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/ida/municipalities/galva/people/gary-wanberg.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Gary Wanberg"
+description: "Mayor, Galva, IA"
+role: "Mayor, Galva, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "5a6da395-71fb-4feb-849a-6c141e847eff"
+  office: "39748af0-3354-4649-9cff-b477dd358f21"
+  tenure: "945f21ee-ad20-4943-befe-10ee0554f296"
+  jurisdiction: "b53bb7d3-f9ec-4c1c-9060-05cc5bf8bc06"
+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"
+---
+
+# Gary Wanberg
+
+Current Mayor, Galva, 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/ida/municipalities/ida-grove/people/nathan-weitl.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Nathan Weitl"
+description: "Mayor, Ida Grove, IA"
+role: "Mayor, Ida Grove, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "331f5cf5-3393-4fea-ac51-c328888dc521"
+  office: "2ad6fe01-efec-43ef-9900-2b5a39fc5071"
+  tenure: "e54ed255-b04d-4425-9939-b01c3025c98f"
+  jurisdiction: "6e357552-d6c8-41b6-aae6-a2e672483fde"
+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"
+---
+
+# Nathan Weitl
+
+Current Mayor, Ida Grove, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).