Use protected password input for seed workflows

[coderabbitai]

Summary

The seed workflows pass PASS on Make command lines and Python process arguments. This can expose passwords in command output and process inspection. Shell expansion can also alter a password before the seed script receives it.

Required changes

• Update server/scripts/seed-users.py and server/scripts/seed-kus.py to read passwords through protected input instead of command-line password arguments.
• Update Docker seed targets and local-development seed targets in Makefile.
• Suppress recipe echoing for every target that handles password input, including aggregate targets such as seed-all and dev-seed-all.
• Preserve the existing username, database, API URL, and Docker/local workflow behaviour.
• Update DEVELOPMENT.md and the quickstart documentation for the revised seed interface.

Rationale

This work changes both the Docker and local-development seed interfaces. It requires a deliberate, documented interface decision outside PR #526.

Affected areas

• Makefile
• server/scripts/seed-users.py
• server/scripts/seed-kus.py
• DEVELOPMENT.md
• Quickstart documentation

Acceptance criteria

• No seed target passes a password as a command-line argument.
• Seed recipes that handle password input do not echo secret-bearing commands.
• Both Docker and local seed workflows work with the protected-input interface.
• Documentation describes the new invocation method.

Backlinks

• Deferred from PR feat(dev): add seed targets for the non-Docker dev server #526: feat(dev): add seed targets for the non-Docker dev server #526
• Review discussion: feat(dev): add seed targets for the non-Docker dev server #526 (comment)
• Requested by @peteski22.