add photo import: upload -> photoprism, fix desktop file dialog

- POST /api/import with native multipart parser (no new deps); stages files
  then delegates indexing+thumbnailing to PhotoPrism via `photoprism cp`
- pathways reflects new photos immediately via refresh()
- upload UI shown only in empty-library state
- nixos: PHOTOPRISM_READONLY=false; pathways service gets STAGING_ROOT and
  photoprism env; PATH includes /run/wrappers/bin so sudo is found
- fix: stage.setPointerCapture was swallowing the import label's click on
  desktop, preventing the native file dialog from opening

1 files changed, 1 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 6659201..5e3e4a4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ node_modules/
 .DS_Store
 *.log
 .env*
+staging/