Make CLI and Textual TUI dependencies optional

## Parent

- #5

## What to build

Implement RFC-0004's package boundary so engine-only consumers install a dependency-free Python SDK while explicit extras provide complete CLI and Textual clients.

## Frozen contract

- Core metadata declares `dependencies = []` and `import oneroll` never imports Rich or Textual.
- `[cli]` installs `rich>=14.1.0`; `[tui]` installs `rich>=14.1.0` and `textual>=6.1.0`.
- The `oneroll` and `1roll` scripts remain, point to a thin standard-library entry point, and do not encode entry-point extras.
- Missing renderer dependencies produce an actionable `install oneroll[cli]` or `install oneroll[tui]` message.
- Cargo remains the authoritative package-version source.

## Acceptance criteria

- [ ] A clean core wheel installs without Rich or Textual and imports Engine successfully.
- [ ] CLI and TUI extras install every dependency required by their entry points.
- [ ] Core-safe script options work without UI extras; unavailable renderers fail clearly without a traceback.
- [ ] Source imports and extension initialization have no optional-presentation dependency.
- [ ] Isolated wheel smoke tests cover core-only, CLI, and TUI installations.

## Blocked by

- #5 human acceptance

Start by reading RFC-0004 and the blocked parent issue #5, then trace the oneroll and 1roll entry points and package metadata. Use isolated wheel smoke tests for core-only, CLI, and TUI installations; done means core imports without Rich or Textual, extras provide their renderer dependencies, and unavailable renderers report the documented install commands without a traceback.

Written by the indexing model from the issue text.