Theming

## Goal

Define and apply Cortext's editing theme: a token contract that styles the shell chrome and, eventually, the editor canvas. The editing theme makes the workspace feel calm and consistent; it does not extend to the public side. Public pages and DataViews render under the active WordPress theme.

## Scope

* Token contract for color, typography, spacing, borders, focus states, and surface treatment.
* Light and dark as the first two Cortext editing themes, with persisted user preference.
* Theme-aware shell areas: sidebar, top bar, dialogs, side peeks, and status UI.
* Theme-aware Cortext blocks, including the DataView block.
* Extending the editing theme into the canvas iframe (Knowledge mode).
* A Knowledge / Site Preview toggle so users can flip the canvas between the Cortext theme and the active WP theme.

## Out of scope

* Theming public pages or DataViews. The active WP theme owns public output.
* Cortext tokens reaching the public frontend.
* Shipping a Cortext WordPress theme for public pages.
* Page icons and covers.
* Per-view collection styling.
* Arbitrary custom CSS editing.

No files, tests, or entry points are identified. Start by locating the shell, Cortext blocks, canvas iframe, and preference persistence, then establish how the active WordPress theme is selected for Site Preview. Done means the token contract, light and dark editing themes, theme-aware areas, persisted preference, and Knowledge/Site Preview toggle are implemented without changing public output.

Written by the indexing model from the issue text.