docs(ui): add full migration table to changeset

Maps every deprecated token to its semantic replacement, grouped by
family: Surfaces, Foreground, Accent, Positive, Negative, Warning,
and Announcement.

Signed-off-by: Charles de Dreuille <charles.dedreuille@gmail.com>

.changeset/ui-semantic-color-tokens.md

@@ -4,4 +4,66 @@
 
 Introduces a new set of semantic color token families — Accent, Announcement, Warning, Negative, and Positive — each providing a consistent set of background, foreground, and border tokens for both light and dark themes. A gray scale (`--bui-gray-1` through `--bui-gray-11`) and updated foreground tokens are also included.
 
-The previous tokens (`--bui-bg-solid-*`, `--bui-bg-neutral-*`, `--bui-bg-danger/warning/success/info`, `--bui-fg-solid`, `--bui-fg-danger/success/info`, `--bui-border-*`, and `--bui-shadow`) remain in place for backward compatibility but are now deprecated and will be removed in a future release.
+The previous tokens remain in place for backward compatibility but are now deprecated and will be removed in a future release. Migrate using the table below.
+
+## Migration
+
+### Surfaces
+
+| Deprecated           | Replacement       |
+| -------------------- | ----------------- |
+| `--bui-bg-app`       | `--bui-surface-1` |
+| `--bui-bg-neutral-1` | `--bui-surface-2` |
+| `--bui-bg-neutral-2` | `--bui-surface-3` |
+| `--bui-bg-neutral-3` | `--bui-surface-4` |
+| `--bui-bg-neutral-4` | `--bui-surface-5` |
+
+### Foreground
+
+| Deprecated         | Replacement             |
+| ------------------ | ----------------------- |
+| `--bui-fg-danger`  | `--bui-fg-negative`     |
+| `--bui-fg-success` | `--bui-fg-positive`     |
+| `--bui-fg-info`    | `--bui-fg-announcement` |
+
+### Accent
+
+| Deprecated                | Replacement                |
+| ------------------------- | -------------------------- |
+| `--bui-bg-solid`          | `--bui-accent-bg`          |
+| `--bui-bg-solid-hover`    | `--bui-accent-bg-hover`    |
+| `--bui-bg-solid-disabled` | `--bui-accent-bg-disabled` |
+| `--bui-fg-solid`          | `--bui-accent-fg`          |
+| `--bui-fg-solid-disabled` | `--bui-accent-fg-disabled` |
+
+### Positive
+
+| Deprecated               | Replacement                 |
+| ------------------------ | --------------------------- |
+| `--bui-bg-success`       | `--bui-positive-bg-subdued` |
+| `--bui-fg-success-on-bg` | `--bui-positive-fg-subdued` |
+| `--bui-border-success`   | `--bui-positive-border`     |
+
+### Negative
+
+| Deprecated              | Replacement                 |
+| ----------------------- | --------------------------- |
+| `--bui-bg-danger`       | `--bui-negative-bg-subdued` |
+| `--bui-fg-danger-on-bg` | `--bui-negative-fg-subdued` |
+| `--bui-border-danger`   | `--bui-negative-border`     |
+
+### Warning
+
+| Deprecated               | Replacement                |
+| ------------------------ | -------------------------- |
+| `--bui-bg-warning`       | `--bui-warning-bg-subdued` |
+| `--bui-fg-warning-on-bg` | `--bui-warning-fg-subdued` |
+| `--bui-border-warning`   | `--bui-warning-border`     |
+
+### Announcement
+
+| Deprecated            | Replacement                     |
+| --------------------- | ------------------------------- |
+| `--bui-bg-info`       | `--bui-announcement-bg-subdued` |
+| `--bui-fg-info-on-bg` | `--bui-announcement-fg-subdued` |
+| `--bui-border-info`   | `--bui-announcement-border`     |