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/md/counties/montgomery/index.md

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

data/jurisdictions/us/states/md/counties/montgomery/municipalities/gaithersburg/people/jud-ashman.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Jud Ashman"
+description: "Mayor, Gaithersburg, MD"
+role: "Mayor, Gaithersburg, MD"
+level: "municipal"
+branch: "executive"
+state: "MD"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "7ccf662b-b082-425f-a354-d5a032061e96"
+  office: "ffd12253-2cfb-4637-bb15-8dad435d565e"
+  tenure: "93a310fd-641a-4081-8240-6a06f610b8a5"
+  jurisdiction: "84b14c05-6103-45f3-9d5a-b1f02ff80808"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, md]
+timestamp: "2026-07-04"
+---
+
+# Jud Ashman
+
+Current Mayor, Gaithersburg, MD.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).

data/jurisdictions/us/states/md/counties/montgomery/municipalities/rockville/people/monique-ashton.md

@@ -0,0 +1,39 @@
+---
+type: Person
+title: "Monique Ashton"
+description: "Mayor, Rockville, MD"
+role: "Mayor, Rockville, MD"
+level: "municipal"
+branch: "executive"
+state: "MD"
+tenure:
+  start: "2026-06-20"
+  current: true
+ids:
+  person: "3e6ea3a5-51d0-435c-99cb-4a93e849fc51"
+  office: "ea48949d-f59a-4a4e-ac3c-a45f3827f961"
+  tenure: "ed1ac816-eab7-42d7-8e99-f6ae2aa14cac"
+  jurisdiction: "e65733ef-8aaa-4ea8-aba5-a8283a2b1fdc"
+sources:
+  - field: office
+    source: "Wikidata"
+  - field: tenure
+    source: "Wikidata"
+  - field: jurisdiction
+    source: "Census TIGER 2024"
+confidence: official
+tags: [officeholder, municipal, executive, md]
+timestamp: "2026-07-04"
+---
+
+# Monique Ashton
+
+Current Mayor, Rockville, MD.
+
+## Sources
+
+- office: Wikidata
+- tenure: Wikidata
+- jurisdiction: Census TIGER 2024
+
+Generated from the Atlas officeholders v3 export (2026-07-04).