chore: ZXDB env validation, MySQL setup, API & UI

This sanity commit wires up the initial ZXDB integration and a minimal UI to explore it.

Key changes:
- Add Zod-based env parsing (`src/env.ts`) validating `ZXDB_URL` as a mysql:// URL (t3.gg style).
- Configure Drizzle ORM with mysql2 connection pool (`src/server/db.ts`) driven by `ZXDB_URL`.
- Define minimal ZXDB schema models (`src/server/schema/zxdb.ts`): `entries` and helper `search_by_titles`.
- Implement repository search with pagination using helper table (`src/server/repo/zxdb.ts`).
- Expose Next.js API route `GET /api/zxdb/search` with Zod query validation and Node runtime (`src/app/api/zxdb/search/route.ts`).
- Create new app section “ZXDB Explorer” at `/zxdb` with search UI, results table, and pagination (`src/app/zxdb/*`).
- Add navbar link to ZXDB (`src/components/Navbar.tsx`).
- Update example.env with readonly-role notes and example `ZXDB_URL`.
- Add drizzle-kit config scaffold (`drizzle.config.ts`).
- Update package.json deps: drizzle-orm, mysql2, zod; devDeps: drizzle-kit. Lockfile updated.
- Extend .gitignore to exclude large ZXDB structure dump.

Notes:
- Ensure ZXDB data and helper tables are loaded (see `ZXDB/scripts/ZXDB_help_search.sql`).
- This commit provides structure-only browsing; future work can enrich schema (authors, labels, publishers) and UI filters.

Signed-off-by: Junie@lucy.xalior.com

src/server/schema/zxdb.ts

@@ -0,0 +1,18 @@
+import { mysqlTable, int, varchar, tinyint, char } from "drizzle-orm/mysql-core";
+
+// Minimal subset needed for browsing/searching
+export const entries = mysqlTable("entries", {
+  id: int("id").notNull().primaryKey(),
+  title: varchar("title", { length: 250 }).notNull(),
+  isXrated: tinyint("is_xrated").notNull(),
+  machinetypeId: tinyint("machinetype_id"),
+  languageId: char("language_id", { length: 2 }),
+});
+
+// Helper table created by ZXDB_help_search.sql
+export const searchByTitles = mysqlTable("search_by_titles", {
+  entryTitle: varchar("entry_title", { length: 250 }).notNull(),
+  entryId: int("entry_id").notNull(),
+});
+
+export type Entry = typeof entries.$inferSelect;