feat(15-01): remove users and sessions tables from schema

- Delete users and sessions table definitions from src/db/schema.ts
- Generate Drizzle migration to drop both tables
- Retain apiKeys, oauthClients, oauthCodes, oauthTokens tables

drizzle/0010_foamy_marvel_zombies.sql

@@ -0,0 +1,2 @@
+DROP TABLE `sessions`;--> statement-breakpoint
+DROP TABLE `users`;

drizzle/meta/_journal.json

@@ -71,6 +71,13 @@
       "when": 1775287060443,
       "tag": "0009_happy_mockingbird",
       "breakpoints": true
+    },
+    {
+      "idx": 10,
+      "version": "6",
+      "when": 1775327900426,
+      "tag": "0010_foamy_marvel_zombies",
+      "breakpoints": true
     }
   ]
 }