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/dubuque/index.md

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

data/jurisdictions/us/states/ia/counties/dubuque/municipalities/asbury/people/jim-adams.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Jim Adams"
+description: "Mayor, Asbury, IA"
+role: "Mayor, Asbury, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "df316b91-f99f-4fa4-9acd-37ecf7c72845"
+  office: "3d4d61fe-6ea7-4fa7-a234-f6180e78c8a9"
+  tenure: "185337cf-0dac-45ea-8fa3-e7f98b809d67"
+  jurisdiction: "ba60a80e-d277-4957-983a-0064d1ed1faa"
+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"
+---
+
+# Jim Adams
+
+Current Mayor, Asbury, 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/dubuque/municipalities/dubuque/people/brad-cavanagh.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Brad Cavanagh"
+description: "Mayor, Dubuque, IA"
+role: "Mayor, Dubuque, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "186c2972-f51e-434e-831c-213d381062d2"
+  office: "4183107f-97a5-487d-a26b-404eac62bd6b"
+  tenure: "10ce10f4-c0e2-400c-b091-e721665d6976"
+  jurisdiction: "d3753b22-cfe5-40b4-a3f6-030f81ffd47b"
+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"
+---
+
+# Brad Cavanagh
+
+Current Mayor, Dubuque, 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/dubuque/municipalities/epworth/people/sandra-gassman.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Sandra Gassman"
+description: "Mayor, Epworth, IA"
+role: "Mayor, Epworth, IA"
+level: "municipal"
+branch: "executive"
+state: "IA"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "3eafeb87-bbd5-49b2-a473-067e3cd6154d"
+  office: "077a5366-40b6-41bc-b407-1530f84b80ad"
+  tenure: "27343af1-b4a3-4039-a6af-45ce7317b018"
+  jurisdiction: "2bbfb39f-dc49-494c-8770-69f1190a42cb"
+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"
+---
+
+# Sandra Gassman
+
+Current Mayor, Epworth, IA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).