Replace password_hash('sha512', rounds=655555) with hash('sha512')
for all 114 secret derivations in group_vars/matrix_servers.

The old method (655k rounds of SHA-512) was designed for protecting
low-entropy human passwords in /etc/shadow. For deriving secrets
from a high-entropy secret key, a single hash round is equally
secure - the security comes from the key's entropy, not the
computational cost. SHA-512 remains preimage-resistant regardless
of rounds.

This yields a major performance improvement: evaluating
postgres_managed_databases (which references multiple derived
database passwords) dropped from ~10.7s to ~0.6s on a fast mini
PC. The Postgres role evaluates this variable multiple times, and
other roles reference derived passwords too, so the cumulative
savings across a full playbook run are substantial.

All derived service passwords (database passwords, appservice
tokens, etc.) will change on the next run. The main/superuser
database password is not affected (it's hardcoded in inventory
variables). All services receive their new passwords in the same
run, so this should be seamless.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>