Add physical dimensions to bin editor for correct aspect ratio

When de-perspectiving a bin photo taken at an angle, inferring the
output size from the quadrilateral shape squishes the result. Entering
real-world W×H (mm) lets the server use the correct aspect ratio,
scaled to the same resolution as the inferred size.

- Bin editor dialog: W×H number inputs, pre-filled from saved phys_w/phys_h
- PUT /api/bins/:id/corners: accepts optional phys_w/phys_h; when provided,
  derives bin_w/bin_h from the physical aspect ratio at equivalent area
- phys_w/phys_h stored on the bin record for re-use on next edit
- future-plans.md: bin types note (reusable dimensions per model)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/lib/api.mjs

@@ -66,7 +66,7 @@ export const get_bins            = () => req('GET', '/api/bins');
 export const create_bin_from_source = (source_id, name) => req('POST', '/api/bins/from-source', { source_id, name });
 export const get_bin         = (id) => req('GET', `/api/bins/${id}`);
 export const rename_bin      = (id, name) => req('PUT', `/api/bins/${id}`, { name });
-export const update_bin_corners = (id, corners) => req('PUT', `/api/bins/${id}/corners`, { corners });
+export const update_bin_corners = (id, corners, phys_w, phys_h) => req('PUT', `/api/bins/${id}/corners`, { corners, phys_w, phys_h });
 export const delete_bin      = (id) => req('DELETE', `/api/bins/${id}`);
 
 export async function upload_bin(file, name) {