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/decatur/index.md

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

data/jurisdictions/us/states/ia/counties/decatur/municipalities/lamoni/people/douglas-l-foster.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Douglas L. Foster"
+description: "Mayor, Lamoni, IA"
+role: "Mayor, Lamoni, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "be5c60c8-362b-468b-8c60-14be0df56849"
+  office: "a2d69ae2-e0d2-447a-9dc1-84e72bf5faad"
+  tenure: "d8bdb9f4-7b06-4069-83d1-018ad0ee6de8"
+  jurisdiction: "fe36c12c-b415-4a30-9ede-9b31486d8903"
+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"
+---
+
+# Douglas L. Foster
+
+Current Mayor, Lamoni, 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/decatur/municipalities/leon/people/bob-frey.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Bob Frey"
+description: "Mayor, Leon, IA"
+role: "Mayor, Leon, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "8b537878-34a2-4d5e-9fb9-dca597fc122a"
+  office: "8b2e04ff-f1f5-4fc4-a1e3-10af06133632"
+  tenure: "8a983033-d747-4a04-8e59-aa03f4cc58c1"
+  jurisdiction: "430fc707-860b-4d41-9679-e986e9c4d396"
+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"
+---
+
+# Bob Frey
+
+Current Mayor, Leon, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).