feat(actions): add GoToNextWord & GoToPrevWord actions

[rudenkornk]

📺 PR Description

Checklist

• my commits and PR title follow the conventional commits format
• if this is a new feature, I have added tests to consolidate the feature and prevent regressions
• if this is a bug fix, I have added a test that reproduces the bug (if applicable)
• I have added a reasonable amount of documentation to the code where appropriate

[Copilot]

Pull request overview

Adds word-wise cursor navigation actions to Television’s input handling and wires them through UI/help and default keybindings.

Changes:

• Introduces GoToNextWord / GoToPrevWord actions and user-facing descriptions.
• Routes these actions through input handling and makes them visible in the help panel.
• Adds default keybindings for word navigation (alt-b, alt-f) in the shipped config.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
television/action.rs	Adds new action variants and descriptions for word navigation.
television/input.rs	Maps new actions to existing InputRequest word-navigation requests.
television/television.rs	Treats new actions as input actions (render + dispatch to handle_input_action).
television/screen/help_panel.rs	Marks new actions as relevant so they appear in help output for supported modes.
.config/config.toml	Adds default keybindings alt-b / alt-f for prev/next word movement.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[rudenkornk]

@alexpasmantier may I ask you to take a look on this PR? :)