www/redmine60: Use puma 7, fix install directories

This commit also modernizes the port's dependencies and configuration
options.

Redmine 6.0 has changed to use a slightly different directory structure
from previous versions. The installation now creates public/assets and
tmp/pdf directories that Redmine 6.x expects, preventing runtime errors
related to missing directories.

Support for Puma 7 allows users to benefit from the latest web server
performance improvements among other enhancements.

Database configuration is now clearer with mutually exclusive options that
prevent misconfiguration. SQLite and SQL Server support give users more
deployment flexibility, though SQLite is clearly marked as unsuitable for
production use.

Use the standardized "PGSQL" naming for PostgreSQL which aligns with
other ports.

The new database.yml.sample patch helps users avoid common configuration
mistakes by providing inline documentation for connection settings, ports,
and encoding options.

PR: 291306