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/il/counties/kane/index.md

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

data/jurisdictions/us/states/il/counties/kane/municipalities/aurora/people/richard-c-irvin.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Richard C. Irvin"
+description: "Mayor, Aurora, IL"
+role: "Mayor, Aurora, IL"
+level: "municipal"
+branch: "executive"
+state: "IL"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "607b5caf-cf21-46d8-933e-a0067ba5b698"
+  office: "24ab6c86-ba0a-4751-8714-3786fb00d91a"
+  tenure: "8de3b917-c3b7-49aa-9b8f-0f85fad286f8"
+  jurisdiction: "17b816c1-8a65-4ec4-aac8-0939e833edef"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, il]
+timestamp: "2026-07-04"
+---
+
+# Richard C. Irvin
+
+Current Mayor, Aurora, IL.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/il/counties/kane/municipalities/elgin/people/dave-kaptain.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Dave Kaptain"
+description: "Mayor, Elgin, IL"
+role: "Mayor, Elgin, IL"
+level: "municipal"
+branch: "executive"
+state: "IL"
+tenure:
+  start: "2011-05-01"
+  current: true
+ids:
+  person: "ba497382-64fc-48de-8bf0-87978ccfef40"
+  office: "5e6e9c39-dec3-42d5-9a52-09f644cc6b8e"
+  tenure: "b1762a6d-024c-4ca5-a4f4-c58fa0e1a92b"
+  jurisdiction: "38a3b7a9-b19a-4e62-9cd2-f4c1b68e8eca"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, il]
+timestamp: "2026-07-04"
+---
+
+# Dave Kaptain
+
+Current Mayor, Elgin, IL.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).