Remove 1Password integration

[jdelfino]

Remove all 1Password integration from the devcontainer template.

Repo: jdelfino/devcontainer-template

Files to remove

• template/.devcontainer/init-1password.sh.jinja
• template/.devcontainer/install-1password-cli.sh
• template/.devcontainer/setup.sh
• template/.devcontainer/setup-secrets.sh.jinja
• template/.env.1password.jinja (if exists)

Files to modify

• copier.yaml: Remove use_1password and op_vault questions, remove _exclude conditionals
• template/.devcontainer/devcontainer.json.jinja: Remove initializeCommand, simplify postStartCommand
• template/.devcontainer/post-create.sh: Remove 1pw CLI install and setup.sh call
• README.md: Remove 1Password setup instructions