Docs: sync pass — match the validator + current architecture

The docs drifted as the project moved fast. Fixed:
- Counts to the validator (canonical): 105,743 records, Jurisdiction 29,905
  (README had 105,746/29,908 — the exact-GEOID backfill dropped 3 city nodes
  and only the commit message was updated, not the docs).
- sources.md: officeholders-v2 → v3 (13,329); added the inputs that landed
  since — municipal GEOID backfill, place/district crosswalks, the complete
  U.S. Code corpus, the executive offices, and the authority edges.
- board.md: it described income/population/poverty only; now names the
  partisan-lean lens, zoom/pan, and the district+representative drill-down.
- data-model.md: stale '17,506 files' → 105,743.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/roadmap.md

@@ -5,7 +5,7 @@ An honest account of what exists, what's next, and what's further out. This repo
 ## Done
 
 - **The substrate** — repo-canonical, OKF markdown + YAML frontmatter, JSON-Schema validated, deterministic build (byte-identical on rerun).
-- **Five entity types, 105,746 files** — Person (13,329), Body (275), Candidate (2,494), Jurisdiction (29,908), LegalText (59,740).
+- **Five entity types, 105,743 files** — Person (13,329), Body (275), Candidate (2,494), Jurisdiction (29,905), LegalText (59,740).
 - **The federal government, structurally** — every member of Congress, the chambers, 49 committees and 181 subcommittees with their leadership, and every member's committee seats.
 - **The nationwide county skeleton** — all 3,131 U.S. counties as demographic nodes, plus all 435 congressional districts (Census ACS demographics on 363).
 - **The authority layer** — every state legislative district (4,927 house, 1,897 senate) linked county↔district↔legislator, nationwide.