chore: exclude generated changelog audit ledgers from Biome (#128)

The changelog generator writes scripts/changelog/audit/<n>.json with
expanded arrays that Biome's formatter rejects, so CI fails on every
changelog draft until someone reformats the file by hand. The ledger is
a generated record and no one edits it, so skip it in the formatter.

Author: nibzard

biome.json

@@ -1,7 +1,8 @@
 {
   "$schema": "https://biomejs.dev/schemas/2.3.3/schema.json",
   "files": {
-    "ignoreUnknown": false
+    "ignoreUnknown": false,
+    "includes": ["**", "!scripts/changelog/audit/**"]
   },
   "formatter": {
     "enabled": true,