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/oh/counties/greene/index.md

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

data/jurisdictions/us/states/oh/counties/greene/municipalities/fairborn/people/dan-kirkpatrick.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Dan Kirkpatrick"
+description: "Mayor, Fairborn, OH"
+role: "Mayor, Fairborn, OH"
+level: "municipal"
+branch: "executive"
+state: "OH"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "f402f1cf-6372-42bc-9a05-88679e7239f4"
+  office: "9da188db-2c95-44ac-9f46-f59fd4b142e4"
+  tenure: "36cd4946-6e39-4a01-a7a3-48e0dd57abc7"
+  jurisdiction: "1a997c58-f0a1-4240-92cc-ea97079f1443"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, oh]
+timestamp: "2026-07-04"
+---
+
+# Dan Kirkpatrick
+
+Current Mayor, Fairborn, OH.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/oh/counties/greene/municipalities/xenia/people/william-urschel.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "William Urschel"
+description: "Mayor, Xenia, OH"
+role: "Mayor, Xenia, OH"
+level: "municipal"
+branch: "executive"
+state: "OH"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "3782adc1-a199-477d-9bd7-4cd11f66eca4"
+  office: "d8a90ce5-fc21-4578-9fb1-1c345a0beb04"
+  tenure: "b1bb37c0-27e1-41ff-8ccc-bffd2e9db368"
+  jurisdiction: "0d391334-5333-409c-8916-71a7b3209fd4"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, oh]
+timestamp: "2026-07-04"
+---
+
+# William Urschel
+
+Current Mayor, Xenia, OH.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).