fix: add mongodb to devDependencies for typecheck resolution

The mongodb driver (#482) was added to optionalDependencies only,
so `tsgo --noEmit` failed with TS2307 when checking the drivers
package. Adding it to devDependencies ensures types are available
during CI typecheck without making it a runtime requirement.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: anandgupta42

bun.lock

@@ -8,6 +8,9 @@
     "./*": "./src/*.ts"
   },
   "files": ["src"],
+  "devDependencies": {
+    "mongodb": "^6.0.0"
+  },
   "optionalDependencies": {
     "pg": "^8.0.0",
     "snowflake-sdk": "^2.0.3",