feat(db): add guild_settings table for per-guild configuration

Store guild-specific settings (roles, channels, moderation options) in
database instead of config file, enabling per-guild configuration and
runtime updates without redeployment.

shared/db/migrations/meta/_journal.json

@@ -29,6 +29,13 @@
       "when": 1770903573324,
       "tag": "0003_new_senator_kelly",
       "breakpoints": true
+    },
+    {
+      "idx": 4,
+      "version": "7",
+      "when": 1770904612078,
+      "tag": "0004_bored_kat_farrell",
+      "breakpoints": true
     }
   ]
 }