Adds `coder secret import <file>` to bulk-import dotenv, JSON, or YAML
secrets through the existing batch API. The command infers the format
from the extension or accepts `--input-format`, supports non-interactive
stdin, validates files locally before upload, and warns when imported
keys cannot be injected as environment variables.
Reviewed and updated by Coder Agents on behalf of @dylanhuff-at-coder.
Adds a coder secret command group for managing user secrets from the
CLI, with create, update, list, and delete subcommands backed by the
existing user secret API.
This branch adds CLI test coverage and refreshes the generated help
output and CLI reference docs for the new command group.
dylanhuff-at-coder