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/tx/counties/polk/index.md

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

data/jurisdictions/us/states/tx/counties/polk/municipalities/livingston/people/judy-b-cochran.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Judy B. Cochran"
+description: "Mayor, Livingston, TX"
+role: "Mayor, Livingston, TX"
+level: "municipal"
+branch: "executive"
+state: "TX"
+tenure:
+  start: "2018-05-15"
+  current: true
+ids:
+  person: "8b64abf7-3454-4840-b86c-43843b0a1485"
+  office: "579f9bed-8441-4fe4-abca-bec7b4887a6f"
+  tenure: "e81a21c9-f059-4959-9f9a-42d9af3d42a1"
+  jurisdiction: "5198e216-af34-469d-ae71-4c1260b229cb"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, tx]
+timestamp: "2026-07-04"
+---
+
+# Judy B. Cochran
+
+Current Mayor, Livingston, TX.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/tx/counties/polk/municipalities/onalaska/people/james-w-arnett.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "James W. Arnett"
+description: "Mayor, Onalaska, TX"
+role: "Mayor, Onalaska, TX"
+level: "municipal"
+branch: "executive"
+state: "TX"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "78738eb9-0be5-4c6a-a147-03a7c4617012"
+  office: "73d146f0-e890-4b8b-8cad-fffe2d51cfbc"
+  tenure: "5a32485a-f376-41fd-bfa8-75ec28a5211a"
+  jurisdiction: "2bb3fac7-1210-4be7-bc43-c0f2dd8c3247"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, tx]
+timestamp: "2026-07-04"
+---
+
+# James W. Arnett
+
+Current Mayor, Onalaska, TX.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).