## ADDED Requirements

### Requirement: Theme switch tracking event
When Umami is enabled, the site MUST emit a custom event when the user changes theme via the theme switcher UI.

The site MUST emit the event using Umami's JavaScript API (`umami.track(...)`) so runtime properties can be included.

The event name MUST be `theme_switch`.

The emitted event MUST include, at minimum:
- `target_id`
- `placement`
- `theme`

#### Scenario: Theme switch emits event
- **WHEN** a user selects `high-contrast` in the theme switcher notch
- **THEN** the site emits a `theme_switch` event with `theme=high-contrast` and a stable `target_id`

#### Scenario: Missing Umami does not break switching
- **WHEN** Umami is not configured or the Umami script is not present
- **THEN** theme switching and persistence still work and no browser error is thrown
