fix: pin baileys to 6.7.21 and fix stale command count test (#193)

The ^6.7.21 caret range resolves to 6.17.16 on fresh npm install, which
ships incompatible TypeScript types (no call signatures on default export).
Pins exact version and adds explicit type annotation on getMessage key param.

Also updates commands.test.ts to expect 5 commands (reset was added but
test still expected 4).

Fixes #192

Written by Cameron ◯ Letta Code

"The caret giveth, and the caret taketh away."

package-lock.json

@@ -45,7 +45,7 @@
       },
       "optionalDependencies": {
         "@slack/bolt": "^4.6.0",
-        "@whiskeysockets/baileys": "^6.7.21",
+        "@whiskeysockets/baileys": "6.7.21",
         "discord.js": "^14.25.1"
       }
     },