feat(deploy): migrations 嵌入二进制，实现真单文件部署

- embed-migrations.ts：扫 ./drizzle/meta/_journal.json，生成 src/server/db/migrations.gen.ts，每条 SQL 通过 `import sql_<idx> from '../../../drizzle/<tag>.sql' with { type: 'text' }` 在 bun build --compile 时被静态嵌入二进制
- migrate.ts 重写：runtime 用 createHash('sha256') 计算迁移哈希，仅用 db.execute(sql) + db.transaction() 公开 API 写入 drizzle.__drizzle_migrations 簿记表（不依赖 @internal 的 db.dialect/db.session）
- db:generate 链 db:embed，保证 SQL 改动总是同步到 migrations.gen.ts
- Dockerfile 删 COPY drizzle/，binary 是部署唯一 artifact
- 同步 README / AGENTS / biome.json

embed-migrations.ts

@@ -0,0 +1,38 @@
+import { existsSync } from 'node:fs'
+import { readFile, writeFile } from 'node:fs/promises'
+
+const JOURNAL = './drizzle/meta/_journal.json'
+const OUTPUT = './src/server/db/migrations.gen.ts'
+const SQL_RELATIVE_FROM_OUTPUT = '../../../drizzle'
+
+type JournalEntry = { idx: number; tag: string; when: number; breakpoints: boolean }
+type Journal = { entries: JournalEntry[] }
+
+const main = async () => {
+  const entries: JournalEntry[] = existsSync(JOURNAL)
+    ? ((JSON.parse(await readFile(JOURNAL, 'utf-8')) as Journal).entries ?? []).sort((a, b) => a.idx - b.idx)
+    : []
+
+  const imports = entries
+    .map((e) => `import sql_${e.idx} from '${SQL_RELATIVE_FROM_OUTPUT}/${e.tag}.sql' with { type: 'text' }`)
+    .join('\n')
+
+  const arrayBody = entries.length
+    ? `[\n${entries.map((e) => `  { tag: '${e.tag}', sql: sql_${e.idx}, when: ${e.when}, breakpoints: ${e.breakpoints} },`).join('\n')}\n]`
+    : '[]'
+
+  const out = `// AUTO-GENERATED by \`bun run db:embed\`. Do not edit.
+${imports ? `${imports}\n` : ''}
+export type EmbeddedMigration = { tag: string; sql: string; when: number; breakpoints: boolean }
+
+export const embeddedMigrations: readonly EmbeddedMigration[] = ${arrayBody}
+`
+
+  await writeFile(OUTPUT, out)
+  console.log(`✓ ${OUTPUT} (${entries.length} migration${entries.length === 1 ? '' : 's'})`)
+}
+
+main().catch((err) => {
+  console.error('❌', err instanceof Error ? err.message : err)
+  process.exit(1)
+})