servers/pfi-postgres: drop stale "Known weak password (rotate)" section

Section claimed gitea + paperless-ng Postgres passwords were "currently
in use" with trivial values and that rotation was pending. Per
STATUS.md: "Rotate exposed secrets — done 2026-04-23. All six rotated:
vaultwarden/gitea/paperless-ng Postgres passwords (hardcoded
compose.yaml literals moved to gitignored .env files in the process)..."

Rotation happened; literals are no longer in compose.yaml; passwords are
no longer trivial. Removing the section rather than amending — once
fixed, there's no value in carrying a "we have weak passwords"
section that lies about the current state.

Surfaced by /tend-docs audit 2026-05-14.

servers/pfi-postgres/README.md

@@ -36,16 +36,6 @@ Shared Postgres server backing multiple ana-docker stacks:
 - **File-level restic on this host:** ❌ not configured. Optional — the
   VM-image + per-consumer pg_dumps together cover most recovery paths.
 
-## Known weak password (rotate)
-
-The inline passwords currently in use for these databases are
-trivially weak:
-- `gitea` / `gitea`
-- `paperless-ng` / `paperless-ng`
-
-Rotation is on the post-backup-pipeline cleanup list. Exposed in the
-2026-04-21 transcripts.
-
 ## Refresh state
 
 ```bash