refactor: convert to bun workspaces monorepo

- Move web app into apps/web/
- Create packages/shared/ with shared types
- Create plugins/decky-vault/ scaffold
- Root package.json manages workspaces only

apps/web/drizzle.config.ts

@@ -0,0 +1,13 @@
+import { config } from "dotenv"
+import { defineConfig } from "drizzle-kit"
+
+config({ path: ".env.local" })
+
+export default defineConfig({
+  schema: "./lib/db/schema/",
+  out: "./drizzle/",
+  dialect: "postgresql",
+  dbCredentials: {
+    url: process.env.DATABASE_URL!,
+  },
+})