feat(db): corp-HQ settlement model + per-settlement population/class bake (T-1074/T-1075, D-242)

Remove the reserved=1 corp-HQ city-pool cross-reference (duplicate co-named cities); corp_specialization keyed on the D-237 vocabulary extended 27->30; authored corp_hq_placement.toml {CityTenant,Standalone} map; headquarters_body backfill via lifted most-populated-body heuristic + body-type tiebreak; standalone HQs emitted as ordinary settlement rows; Zipf rank-size population spread from bodies.population at import; settlement_class defaults PopulationBudget + settlement_name_locked.toml hero pins; retire orphaned populate-corporations.sh; regen systems.db.

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

server/data/systems-schema.sql

@@ -238,8 +238,11 @@ CREATE TABLE IF NOT EXISTS corporations (
     corp_type TEXT NOT NULL,            -- corporation, combine, syndic, institution, independent
     scope TEXT,                         -- reach-wide, sector, system, local
     headquarters_system TEXT REFERENCES star_systems(system_id),
-    headquarters_body TEXT,             -- body_id or station_id
-    specialization TEXT,                -- primary product/service
+    headquarters_body TEXT,             -- body_id or station_id (D-242: backfilled at import for
+                                         -- every corp via the most-populated-body-in-system heuristic
+                                         -- when not authored; see populate_corp_specialization)
+    specialization TEXT,                -- free-text primary product/service (legacy prose; read by
+                                         -- generate_corporations for fuzzy brand relevance — left as-is)
     parent_corp TEXT REFERENCES corporations(corp_id),
     notes TEXT,
 
@@ -248,6 +251,19 @@ CREATE TABLE IF NOT EXISTS corporations (
     supply_chain_role TEXT,
     shadow_economy_access INTEGER DEFAULT 0,
 
+    -- D-242: controlled-vocabulary corp specialization (HQ-placement key) + its
+    -- baked placement outcome. corp_specialization is the corp_specialization
+    -- controlled vocabulary (reuses the D-237 27-value specialization_vocabulary
+    -- id-space — see wiki/economics/corp_hq_placement.toml header). hq_placement
+    -- is 'CityTenant' | 'Standalone', derived once at import from corp_specialization
+    -- via the authored placement map; NULL until populate_corp_specialization runs.
+    -- headquarters_city_id is the D-242 "corp -> city link" for CityTenant HQs
+    -- (many corps may tenant one city); NULL for Standalone HQs (which instead
+    -- get their own atlas_city_names row, cross-referenced by headquarters_body).
+    corp_specialization TEXT,
+    hq_placement TEXT,
+    headquarters_city_id INTEGER REFERENCES atlas_city_names(id),
+
     updated_at TEXT DEFAULT (datetime('now'))
 );
 
@@ -493,6 +509,10 @@ CREATE INDEX IF NOT EXISTS idx_atlas_mountain_ranges_body ON atlas_mountain_rang
 
 -- City name reservations — replaces authored city positions in markers.json (D-207, #902)
 -- Position is generated by the city placement algorithm; name is authored or LLM-generated.
+-- D-242: a Standalone corp HQ IS a settlement, so it gets an ordinary row here
+-- (populate_standalone_hq_settlements) — same shape as a wiki-pooled city, no
+-- special kind/flag. A CityTenant HQ is NOT a row here; its corp->city link
+-- lives on corporations.headquarters_city_id (the inverse FK) instead.
 CREATE TABLE IF NOT EXISTS atlas_city_names (
     id               INTEGER PRIMARY KEY AUTOINCREMENT,
     body_id          TEXT NOT NULL REFERENCES bodies(body_id) ON DELETE CASCADE,
@@ -500,8 +520,15 @@ CREATE TABLE IF NOT EXISTS atlas_city_names (
     kind             TEXT NOT NULL DEFAULT 'city',          -- 'capital' | 'city'
     economic_role    TEXT NOT NULL,
     population       INTEGER NOT NULL,
-    settlement_class TEXT,                                  -- D-196 SettlementClass variant; NULL until placement
-    corp_id          TEXT REFERENCES corporations(corp_id), -- nullable, corp HQ if applicable
+    settlement_class TEXT,                                  -- D-196 SettlementClass variant; baked at import (D-242/T-1075)
+    corp_id          TEXT REFERENCES corporations(corp_id), -- SUPERSEDED (D-242): the D-207/D-223 corp-HQ
+                                                             -- cross-reference insert that populated this is
+                                                             -- removed (it produced duplicate co-named "cities" —
+                                                             -- one row per corp HQ, no UNIQUE(body_id, name)).
+                                                             -- Always NULL going forward; the corp<->settlement
+                                                             -- relationship now lives on corporations
+                                                             -- (headquarters_body / headquarters_city_id). Column
+                                                             -- kept (not dropped) — additive-safe, no live reader.
     reserved         INTEGER NOT NULL DEFAULT 0,            -- 1 = reserved for authored scenario use
     updated_at       TEXT NOT NULL DEFAULT (datetime('now'))
 );