Add od-backup-verify runbook: isolated Hyper-V test-restore + health checklist

Verify an od-db-backup cold backup by restoring it into a throwaway,
network-isolated Hyper-V VM (revert to checkpoint after), never over live
prod. Covers matching versions from MANIFEST, whole-datadir restore for
InnoDB, re-pointing the image path, and a pass/fail health checklist
(connects, Help>About version, Database Maintenance Check, recent data,
images open, no missing tables, optional mysqlcheck). Cites Open Dental
Backups / Manual Backups / Database Maintenance. Cross-linked with
od-db-backup.md; README updated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -69,6 +69,7 @@ run time — never commit filled-in values.
 | [`od-cfg-persist.md`](od-cfg-persist.md) | Open Dental — persist "Do not show this window on startup" (writable FreeDentalConfig.xml) |
 | [`od-scan-duplex.md`](od-scan-duplex.md) | Open Dental — duplex ADF scanner captures only one side (TWAIN, Show TWAIN UI branches) |
 | [`od-db-backup.md`](od-db-backup.md) | Open Dental — rock-solid cold backup of the database + images (stop/copy/start MySQL/MariaDB) |
+| [`od-backup-verify.md`](od-backup-verify.md) | Open Dental — verify a backup by test-restoring into an isolated Hyper-V VM (health checklist) |
 | [`scripts/cg-disable.ps1`](scripts/cg-disable.ps1) | Disable Credential Guard, then reboot (prompts to confirm) |
 | [`scripts/od-cfg-acl.ps1`](scripts/od-cfg-acl.ps1) | Grant Users Modify on FreeDentalConfig.xml (Option B of od-cfg-persist) |
 | [`scripts/od-db-backup.ps1`](scripts/od-db-backup.ps1) | Cold backup: stop MySQL/MariaDB, copy whole data dir + OpenDentImages, always restart (od-db-backup) |