Add elections + demographics layer: candidates and jurisdictions

Two new entity types, built deterministically from the raw exports:

  Candidate (2,494)     — 2026 federal candidates as files under
                          us/states/<st>/candidates/, with office,
                          district, party, incumbent/challenger stance,
                          campaign committee, FEC id.

  Jurisdiction (3,494)  — demographic nodes carrying ACS 2023 data:
                          3,131 counties (deduped from 3,231 mixed-format
                          fips keys) + 363 congressional districts.

This completes the county skeleton nationwide: every US county is now a
browsable node with population, income, poverty, race, education and
housing — even where no officeholders are mapped yet. In Florida the
county index.md merges into the existing dir and reports its officeholder
count alongside demographics (St. Lucie: 33 officeholders + ACS profile).

build.py now reads seven raw inputs in one deterministic pass
(byte-identical on rerun). The mirror now answers: who holds power, who
runs this institution, who is running, and what each place is made of.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

data/jurisdictions/us/states/nh/districts/01.md

@@ -0,0 +1,59 @@
+---
+type: Jurisdiction
+title: "NH-01"
+classification: congressional-district
+state: "NH"
+district: "NH-01"
+demographics:
+  population: 708843
+  population_under_18: 145765
+  population_18_64: 223019
+  population_65_plus: 340059
+  median_household_income: 102258
+  poverty_rate: 7.09
+  homeownership_rate: 71.99
+  unemployment_rate: 2.61
+  median_home_value: 487000
+  gini_index: 0.443
+  vacancy_rate: 13.51
+  race_white: 624757
+  race_black: 10930
+  race_asian: 15006
+  hispanic: 37984
+  bachelors_plus: 224656
+sources:
+  - field: demographics
+    source: Census ACS 2023
+confidence: official
+tags: [jurisdiction, congressional-district, nh]
+timestamp: "2026-07-03"
+---
+
+# NH-01
+
+Congressional district NH-01.
+
+## Demographics (ACS 2023)
+
+| Measure | Value |
+| --- | --- |
+| Population | 708843 |
+| Under 18 | 145765 |
+| 18–64 | 223019 |
+| 65+ | 340059 |
+| Median household income | 102258 |
+| Poverty rate | 7.09 |
+| Homeownership rate | 71.99 |
+| Unemployment rate | 2.61 |
+| Median home value | 487000 |
+| Gini index | 0.443 |
+| Vacancy rate | 13.51 |
+| White | 624757 |
+| Black | 10930 |
+| Asian | 15006 |
+| Hispanic/Latino | 37984 |
+| Bachelor's or higher | 224656 |
+
+## Source
+
+- demographics: Census ACS 2023

data/jurisdictions/us/states/nh/districts/02.md

@@ -0,0 +1,59 @@
+---
+type: Jurisdiction
+title: "NH-02"
+classification: congressional-district
+state: "NH"
+district: "NH-02"
+demographics:
+  population: 700189
+  population_under_18: 141959
+  population_18_64: 217121
+  population_65_plus: 341109
+  median_household_income: 97020
+  poverty_rate: 7.32
+  homeownership_rate: 73.16
+  unemployment_rate: 2.95
+  median_home_value: 430000
+  gini_index: 0.4523
+  vacancy_rate: 12.81
+  race_white: 608981
+  race_black: 10343
+  race_asian: 22841
+  hispanic: 32928
+  bachelors_plus: 206319
+sources:
+  - field: demographics
+    source: Census ACS 2023
+confidence: official
+tags: [jurisdiction, congressional-district, nh]
+timestamp: "2026-07-03"
+---
+
+# NH-02
+
+Congressional district NH-02.
+
+## Demographics (ACS 2023)
+
+| Measure | Value |
+| --- | --- |
+| Population | 700189 |
+| Under 18 | 141959 |
+| 18–64 | 217121 |
+| 65+ | 341109 |
+| Median household income | 97020 |
+| Poverty rate | 7.32 |
+| Homeownership rate | 73.16 |
+| Unemployment rate | 2.95 |
+| Median home value | 430000 |
+| Gini index | 0.4523 |
+| Vacancy rate | 12.81 |
+| White | 608981 |
+| Black | 10343 |
+| Asian | 22841 |
+| Hispanic/Latino | 32928 |
+| Bachelor's or higher | 206319 |
+
+## Source
+
+- demographics: Census ACS 2023