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/dallas/index.md

@@ -32,7 +32,7 @@ timestamp: "2026-07-03"
 
 # Dallas County, IA
 
-County jurisdiction.
+County jurisdiction — 3 officeholders mapped.
 
 ## Demographics (ACS 2023)
 

data/jurisdictions/us/states/ia/counties/dallas/municipalities/adel/people/james-f-peters.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "James F. Peters"
+description: "Mayor, Adel, IA"
+role: "Mayor, Adel, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "25515a2b-0b72-47e6-b7e8-0d213fe16728"
+  office: "b518d988-dfd5-4639-89c9-4bdceda9096a"
+  tenure: "c484cbc8-a4b4-42d5-b057-c49abff7ae06"
+  jurisdiction: "d9f00b6c-277f-4267-a9ed-917e71e6f193"
+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"
+---
+
+# James F. Peters
+
+Current Mayor, Adel, 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/dallas/municipalities/dexter/people/dennis-clemetson.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Dennis Clemetson"
+description: "Mayor, Dexter, IA"
+role: "Mayor, Dexter, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "9be23ed8-5d9e-4ffd-94c7-7d6d6f03dca8"
+  office: "d55876c4-d828-4922-a962-9c49c1fac14a"
+  tenure: "2989408d-b2ea-46d8-ab24-f01bc3fafe6d"
+  jurisdiction: "140b91f4-7740-4fbb-a0c8-a4b8562d5685"
+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"
+---
+
+# Dennis Clemetson
+
+Current Mayor, Dexter, 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/dallas/municipalities/waukee/people/courtney-clarke.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Courtney Clarke"
+description: "Mayor, Waukee, IA"
+role: "Mayor, Waukee, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "465d1d7a-d093-44a8-8912-76bceefe9412"
+  office: "c9b16549-895d-4e51-a5d0-7146a4a751e9"
+  tenure: "d3b97eb6-88ec-4a58-b88c-d1308f145fbe"
+  jurisdiction: "3655ae8d-b034-4832-80d9-a3a2ca8b689e"
+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"
+---
+
+# Courtney Clarke
+
+Current Mayor, Waukee, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).