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/black-hawk/index.md

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

data/jurisdictions/us/states/ia/counties/black-hawk/municipalities/cedar-falls/people/danny-laudick.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Danny Laudick"
+description: "Mayor, Cedar Falls, IA"
+role: "Mayor, Cedar Falls, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2024-01-02"
+  current: true
+ids:
+  person: "54700634-d24b-4f1a-8553-c27a634eb6b0"
+  office: "df56480d-1d19-4137-8073-27edd86b3ba9"
+  tenure: "db5c6600-7857-46f1-8853-def076674c64"
+  jurisdiction: "79c736dd-c00f-4efc-8de8-99d7da750b4c"
+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"
+---
+
+# Danny Laudick
+
+Current Mayor, Cedar Falls, 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/black-hawk/municipalities/waterloo/people/quentin-m-hart.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Quentin M. Hart"
+description: "Mayor, Waterloo, IA"
+role: "Mayor, Waterloo, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "67364258-e5c2-4b80-8837-0a1de53fd0e6"
+  office: "5dc831cf-d43c-49de-9e48-710bfacc6396"
+  tenure: "e6c99e65-fdbb-4efc-aa02-a379e8d02711"
+  jurisdiction: "2a1b0d97-7146-40a0-af1e-1fe1ac8ae662"
+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"
+---
+
+# Quentin M. Hart
+
+Current Mayor, Waterloo, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).