fix(db): repair mysql migration metadata so drizzle-kit works again

0042_snapshot.json spelled one table's check-constraint key
`checkConstraints` instead of `checkConstraint`. drizzle-kit rejects the
whole folder over it and exits 0 with only a printed message, so
`migration:mysql:generate` has silently produced nothing since #6192.

Every mysql migration authored since then was therefore hand-written with
no snapshot, including 0044 and 0045. Without those snapshots the next
generate diffs against 0043 and re-emits the assistant tables.

Adds the two missing snapshots and a test covering the invariants: journal
and .sql files agree both ways, every entry has a snapshot, indexes are
gap-free, and snapshots agree on the key spelling. The same test would have
caught the v1.70.0 release that shipped 0042_add_widget_secret.sql without
a journal entry, leaving upgraded MySQL instances with no widget_secret
table.

packages/db/migrations/mysql/meta/0042_snapshot.json

@@ -2627,7 +2627,7 @@
         }
       },
       "uniqueConstraints": {},
-      "checkConstraints": {}
+      "checkConstraint": {}
     }
   },
   "views": {},

packages/db/test/migration-journal.spec.ts

@@ -0,0 +1,98 @@
+import fs from "fs";
+import path from "path";
+import { describe, expect, test } from "vitest";
+
+/**
+ * Guards the migration folders against the failure modes that have actually shipped:
+ *
+ * - v1.70.0 shipped `0042_add_widget_secret.sql` for MySQL without a `_journal.json` entry, so the
+ *   migrator never ran it and MySQL instances upgraded from that release had no `widget_secret`
+ *   table.
+ * - The follow-up fix hand-wrote `0042_snapshot.json` with a `checkConstraints` key instead of
+ *   `checkConstraint`, which made `drizzle-kit generate` reject the folder and silently exit 0 for
+ *   every later MySQL migration.
+ */
+const dialects = ["mysql", "postgresql", "sqlite"] as const;
+
+const migrationsRoot = path.join(__dirname, "..", "migrations");
+
+interface Journal {
+  entries: { idx: number; tag: string }[];
+}
+
+const readDialect = (dialect: (typeof dialects)[number]) => {
+  const folder = path.join(migrationsRoot, dialect);
+  const journal = JSON.parse(fs.readFileSync(path.join(folder, "meta", "_journal.json"), "utf8")) as Journal;
+  const sqlFiles = fs
+    .readdirSync(folder)
+    .filter((file) => file.endsWith(".sql"))
+    .map((file) => file.replace(/\.sql$/u, ""));
+  const snapshots = fs
+    .readdirSync(path.join(folder, "meta"))
+    .filter((file) => /^\d+_snapshot\.json$/u.test(file))
+    .map((file) => file.split("_")[0]);
+
+  return { folder, journal, sqlFiles, snapshots };
+};
+
+describe.each(dialects)("%s migrations", (dialect) => {
+  test("every journal entry has a matching .sql file", () => {
+    const { journal, sqlFiles } = readDialect(dialect);
+    const missing = journal.entries.filter((entry) => !sqlFiles.includes(entry.tag)).map((entry) => entry.tag);
+
+    expect(missing).toEqual([]);
+  });
+
+  test("every .sql file is registered in the journal", () => {
+    const { journal, sqlFiles } = readDialect(dialect);
+    const tags = new Set(journal.entries.map((entry) => entry.tag));
+    const orphans = sqlFiles.filter((file) => !tags.has(file));
+
+    expect(orphans).toEqual([]);
+  });
+
+  test("every journal entry has a matching snapshot", () => {
+    const { journal, snapshots } = readDialect(dialect);
+    const missing = journal.entries
+      .filter((entry) => !snapshots.includes(String(entry.idx).padStart(4, "0")))
+      .map((entry) => entry.tag);
+
+    expect(missing).toEqual([]);
+  });
+
+  test("journal indexes are unique and gap-free", () => {
+    const { journal } = readDialect(dialect);
+    const indexes = journal.entries.map((entry) => entry.idx);
+
+    expect(indexes).toEqual(indexes.map((_, position) => position));
+  });
+
+  // The check-constraint key is spelled differently per snapshot format version (MySQL's v5 uses
+  // `checkConstraint`, the newer SQLite/Postgres formats use `checkConstraints`), so rather than
+  // hard-coding a spelling this asserts every snapshot in a dialect agrees with the others. A
+  // hand-written snapshot that gets it wrong stands out as the odd one and fails drizzle-kit.
+  test("all snapshots agree on the check-constraint key spelling", () => {
+    const { folder, snapshots } = readDialect(dialect);
+
+    const spellingsPerSnapshot = snapshots.map((snapshot) => {
+      const file = path.join(folder, "meta", `${snapshot}_snapshot.json`);
+      const parsed = JSON.parse(fs.readFileSync(file, "utf8")) as { tables?: Record<string, object> };
+      const spellings = new Set<string>();
+
+      for (const table of Object.values(parsed.tables ?? {})) {
+        if ("checkConstraint" in table) spellings.add("checkConstraint");
+        if ("checkConstraints" in table) spellings.add("checkConstraints");
+      }
+
+      return { snapshot, spellings: [...spellings].toSorted().join("+") };
+    });
+
+    const used = [...new Set(spellingsPerSnapshot.map((entry) => entry.spellings))].filter(
+      (spelling) => spelling.length > 0,
+    );
+
+    expect(used, `snapshots disagree: ${JSON.stringify(spellingsPerSnapshot.filter((e) => e.spellings))}`).toHaveLength(
+      1,
+    );
+  });
+});