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/marshall/index.md

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

data/jurisdictions/us/states/ia/counties/marshall/municipalities/marshalltown/people/joel-t-s-greer.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Joel T.S. Greer"
+description: "Mayor, Marshalltown, IA"
+role: "Mayor, Marshalltown, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "55239930-94d2-4092-b70a-792b9ab5cb1e"
+  office: "b75bc159-b7f0-4669-ac9f-0599efcb2870"
+  tenure: "9537523a-da39-45c0-a6f8-0071bb1a0522"
+  jurisdiction: "3fe970e3-a51f-4e32-af7a-7035d580496d"
+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"
+---
+
+# Joel T.S. Greer
+
+Current Mayor, Marshalltown, 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/marshall/municipalities/melbourne/people/cynthia-mansager.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Cynthia Mansager"
+description: "Mayor, Melbourne, IA"
+role: "Mayor, Melbourne, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "9f15f60c-a234-44c0-a56d-526b6060b361"
+  office: "03cf8bf8-5700-4166-b864-b436fd638161"
+  tenure: "5343b591-ee37-404e-a8a5-790ab64b0a55"
+  jurisdiction: "1d75d7ca-eb8e-4d96-b3cd-40f23428b89f"
+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"
+---
+
+# Cynthia Mansager
+
+Current Mayor, Melbourne, 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/marshall/municipalities/state-center/people/craig-pfantz.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Craig Pfantz"
+description: "Mayor, State Center, IA"
+role: "Mayor, State Center, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2022-01-01"
+  current: true
+ids:
+  person: "0f3bb4af-7dab-4fe0-b84d-caf3238409ab"
+  office: "89b284e8-d8f0-403e-9eb1-03202a545c8f"
+  tenure: "e235a5a2-09f0-43cd-9e4b-56baf4fd616c"
+  jurisdiction: "256fdb87-8655-46f9-a791-7cb0b5920571"
+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"
+---
+
+# Craig Pfantz
+
+Current Mayor, State Center, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).