Add --version flag to jitsudo CLI and jitsudod server

[youshibin]

Problem

Running jitsudo --version or jitsudo version returns an error:

```
Error: unknown flag: --version
Error: unknown command "version" for "jitsudo"
```

Same issue applies to jitsudod. Users have no way to confirm which version they have installed from the CLI itself (other than brew info jitsudo for Homebrew installs).

Proposed solution

Add a --version flag (or version subcommand) to both jitsudo and jitsudod that prints the installed version, e.g.:

```
jitsudo v0.1.0
jitsudod v0.1.0
```

The version string is already injected at build time via -ldflags (internal/version.Version), so this should be straightforward to wire up in both root Cobra commands.