Add Vault auto-unseal service and 1Password bootstrap script

Add vault-tpm2-unseal.sh/.service to unseal Vault once after boot using
the TPM-sealed key, and tpm-bootstrap-1password.sh to (re)seal that key
from a 1Password secret reference. Document PCR policy selection, the
Vault service, and the host-specific tpm2.env (gitignored, example in
README) in README.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1 @@
+*.env