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/mi/counties/oakland/index.md

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

data/jurisdictions/us/states/mi/counties/oakland/municipalities/rochester-hills/people/bryan-barnett.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Bryan Barnett"
+description: "Mayor, Rochester Hills, MI"
+role: "Mayor, Rochester Hills, MI"
+level: "municipal"
+branch: "executive"
+state: "MI"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "57bffe2f-2f6a-473c-9153-8ee2cdb570ac"
+  office: "f1295cae-dfc9-4e19-9208-a499755ca65d"
+  tenure: "b3e9db3b-e200-436c-ac55-ef307d23650a"
+  jurisdiction: "96493bff-a27b-4ad7-baca-f1849d122963"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, mi]
+timestamp: "2026-07-04"
+---
+
+# Bryan Barnett
+
+Current Mayor, Rochester Hills, MI.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/mi/counties/oakland/municipalities/southfield/people/kenson-siver.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Kenson Siver"
+description: "Mayor, Southfield, MI"
+role: "Mayor, Southfield, MI"
+level: "municipal"
+branch: "executive"
+state: "MI"
+tenure:
+  start: "2015-11-16"
+  current: true
+ids:
+  person: "6d358c16-3419-4e04-aaf8-ee74ae82952c"
+  office: "2ea940c5-6fef-4199-98a5-53510d997b7a"
+  tenure: "ca069a94-0ea0-4b8c-b84d-c843a8eb7b22"
+  jurisdiction: "f463c5aa-e2ed-4188-b7fa-4dfe9ef7c9e0"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, mi]
+timestamp: "2026-07-04"
+---
+
+# Kenson Siver
+
+Current Mayor, Southfield, MI.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/mi/counties/oakland/municipalities/troy/people/ethan-baker.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Ethan Baker"
+description: "Mayor, Troy, MI"
+role: "Mayor, Troy, MI"
+level: "municipal"
+branch: "executive"
+state: "MI"
+tenure:
+  start: "2019-11-01"
+  current: true
+ids:
+  person: "8f77c686-1e67-4d98-9ef0-e7ff2569971f"
+  office: "b8ffe34b-32b7-4c87-9f9d-d08d5937dad1"
+  tenure: "7b0f30e3-ef07-4026-87b1-baac783361ab"
+  jurisdiction: "1c9421ca-6c8e-4351-8c06-8d4023a7d58a"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, mi]
+timestamp: "2026-07-04"
+---
+
+# Ethan Baker
+
+Current Mayor, Troy, MI.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).