feat: media picker and image removal

features/editor_image_crop_resize.qa.md

@@ -18,7 +18,7 @@ it renders internally (canvas/OffscreenCanvas is a coder implementation detail).
    "1600 px" selected, mono line "Uploads as 1600 × 1200 px · about 420 KB", footer "Choose
    another file" / "Upload image".
 2. **An SVG bypasses the step** — choose `diagram.svg` (image/svg+xml, 40 KB); assert an XHR to
-   `/v1/article/12/image` is created immediately and the crop step never renders.
+   `/v1/media/` is created immediately and the crop step never renders.
 3. **Ratio presets lock the frame, Examples-driven (16:9 / 4:3 / 1:1)** — from the opened step,
    select each ratio pill; assert the frame's reported rect and the mono line's output size match
    the feature's Examples table.