feat(api): add auditable map revision history

api/schema.sql

@@ -652,3 +652,29 @@ CREATE INDEX IF NOT EXISTS idx_game_map_tile_entities_map
     ON game_map_tile_entities(map_num, status);
 CREATE INDEX IF NOT EXISTS idx_game_uploaded_graphics_created_at
     ON game_uploaded_graphics(created_at DESC);
+
+-- Historial auditable de las ediciones de mapas. Se almacenan los estados
+-- anterior y posterior de la vista dispersa del mapa: esto mantiene el
+-- historial exacto sin copiar los 10.000 tiles originales.
+CREATE TABLE IF NOT EXISTS game_map_revisions (
+    id BIGSERIAL PRIMARY KEY,
+    map_num INTEGER NOT NULL CHECK (map_num > 0),
+    operation TEXT NOT NULL CHECK (operation IN ('paint', 'clear', 'publish', 'discard', 'revert', 'undo', 'redo', 'rollback')),
+    author_account_id UUID REFERENCES accounts(id) ON DELETE SET NULL,
+    before_state JSONB NOT NULL,
+    after_state JSONB NOT NULL,
+    metadata JSONB NOT NULL DEFAULT '{}'::jsonb,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE TABLE IF NOT EXISTS game_map_revision_heads (
+    map_num INTEGER PRIMARY KEY CHECK (map_num > 0),
+    current_revision_id BIGINT REFERENCES game_map_revisions(id) ON DELETE SET NULL,
+    redo_revision_id BIGINT REFERENCES game_map_revisions(id) ON DELETE SET NULL,
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_game_map_revisions_map_created
+    ON game_map_revisions(map_num, created_at DESC, id DESC);
+CREATE INDEX IF NOT EXISTS idx_game_map_revisions_author
+    ON game_map_revisions(author_account_id, created_at DESC);