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/ma/counties/suffolk/index.md

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

data/jurisdictions/us/states/ma/counties/suffolk/municipalities/boston/people/michelle-wu.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Michelle Wu"
+description: "Mayor, Boston, MA"
+role: "Mayor, Boston, MA"
+level: "municipal"
+branch: "executive"
+state: "MA"
+tenure:
+  start: "2021-11-16"
+  current: true
+ids:
+  person: "772a7f25-24e5-414b-9e4d-e6f2a9b39e50"
+  office: "5e7f4631-a8bd-4fcc-85d9-c8bce973442c"
+  tenure: "4c869b20-aa4c-4a0f-8f7f-7f0f57d7081a"
+  jurisdiction: "c8b3a0a7-5688-47f0-b459-39008024eae4"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, ma]
+timestamp: "2026-07-04"
+---
+
+# Michelle Wu
+
+Current Mayor, Boston, MA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/ma/counties/suffolk/municipalities/revere/people/patrick-m-keefe-jr.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Patrick M. Keefe Jr."
+description: "Mayor, Revere, MA"
+role: "Mayor, Revere, MA"
+level: "municipal"
+branch: "executive"
+state: "MA"
+tenure:
+  start: "2023-11-07"
+  current: true
+ids:
+  person: "7478dd80-8832-42eb-9043-d56ecb458d06"
+  office: "b7bcdc07-20ca-4b2f-b007-871017005eb3"
+  tenure: "8004ad9b-9c66-4844-b679-e1c0643457c8"
+  jurisdiction: "09d72661-3046-412f-8584-c922f9ab0dbd"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, ma]
+timestamp: "2026-07-04"
+---
+
+# Patrick M. Keefe Jr.
+
+Current Mayor, Revere, MA.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).