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/linn/index.md

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

data/jurisdictions/us/states/ia/counties/linn/municipalities/cedar-rapids/people/tiffany-o-donnell.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Tiffany O'Donnell"
+description: "Mayor, Cedar Rapids, IA"
+role: "Mayor, Cedar Rapids, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2022-01-01"
+  current: true
+ids:
+  person: "ee1de885-7629-4f1a-935f-192baed56cb3"
+  office: "4cffb919-9bba-49e3-aa62-4c929a2d648c"
+  tenure: "8a54a719-9731-4a24-99c7-be7ddbc529f9"
+  jurisdiction: "128623a1-6d4e-4dbf-be92-96427f783228"
+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"
+---
+
+# Tiffany O'Donnell
+
+Current Mayor, Cedar Rapids, 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/linn/municipalities/marion/people/nicolas-abouassaly.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Nicolas AbouAssaly"
+description: "Mayor, Marion, IA"
+role: "Mayor, Marion, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2015-11-01"
+  current: true
+ids:
+  person: "76ed19ec-1f38-421d-8639-ecff85d393df"
+  office: "80e1b1b8-3766-4fb3-a778-7971b72e5a86"
+  tenure: "92f894ae-2f7b-489b-b997-aca0b9017fc1"
+  jurisdiction: "5de28a42-f6d8-43e3-8aca-7e972dcc17a4"
+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"
+---
+
+# Nicolas AbouAssaly
+
+Current Mayor, Marion, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).