chore(db): finish Prisma cutover to Drizzle Kit tooling

Move CMS SQL to drizzle/migrations, drop prisma packages/schema, wire drizzle-kit scripts, and regenerate schema names from src/db/schema.ts.

Co-authored-by: Cursor <[email protected]>

drizzle/migrations/0006_writeable_boxes.sql

@@ -0,0 +1,13 @@
+-- CMS-owned editable content boxes (AtomCMS WriteableBox). Rendered on the
+-- public site and managed from housekeeping. Idempotent (MariaDB).
+CREATE TABLE IF NOT EXISTS website_writeable_boxes (
+  id         BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
+  title      VARCHAR(255) NOT NULL,
+  icon       VARCHAR(255) NULL,
+  content    TEXT NOT NULL,
+  position   INT NOT NULL DEFAULT 0,
+  is_active  TINYINT(1) NOT NULL DEFAULT 1,
+  created_at TIMESTAMP NULL,
+  updated_at TIMESTAMP NULL,
+  PRIMARY KEY (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;