wire up photo upload on donation details submission (REP-49)

[stephenhungg]

Summary

Closes REP-49 on the mobile side. Captures the selected photo URI in state and sends it through the completion endpoint as multipart/form-data. Pairs with backend PR replate/replate-business#2803 which adds the Paperclip attachment on Task.

Changes

src/app/donation-details/[id].tsx

• New photoUri state (string | null), wired into PhotoUpload.onSelect={setPhotoUri} (was a no-op before).
• handleComplete passes photoUri into submitCompletionDetails.

api/config.ts

• submitCompletionDetails now accepts optional photoUri. When present, it switches from JSON to FormData:
  • Fields sent as task[total_pounds_entered], task[description], task[photo] because the backend's wrap_parameters is JSON-only, so keys need to be pre-wrapped for multipart to land under params["task"][...].
  • Photo appended as {uri, name, type} — React Native's FormData convention for file uploads. Filename and mime inferred from the expo-image-picker URI (defaults to image/jpeg, switches to image/png on .png).
  • Content-Type header is intentionally omitted so fetch sets it to multipart/form-data; boundary=... automatically — setting it manually breaks the boundary.
• When no photo: falls through to the original JSON path, unchanged behavior.

Base branch

Targeting stephenhung/rep-41-connect-my-tasks-details because the issue's dev workflow says to branch off the previous sprint's branch. This is a stacked PR — REP-41 should land first, then this rebases onto design-system-overhaul (or main depending on how REP-41 gets merged).

Notes / flags

• apiRequest calls response.json() on a 204 No Content response — the endpoint returns head 204, which will make response.json() throw on an empty body. This is a latent bug from before REP-49, not something this PR introduces. The error gets swallowed by the try/catch in handleComplete, so the user still sees "Donation recorded!" and the redirect fires. Worth fixing in a follow-up.
• FormData typing: RN's FormData.append accepts {uri, name, type} file objects, but TypeScript's DOM types only accept Blob | string. Used as unknown as Blob which is the standard workaround.

Test plan

• pnpm tsc clean
• pnpm lint:check clean
• pnpm prettier:check clean
• husky pre-commit hook passed
• Not manually tested — see below
• Select photo → tap Complete → confirm Task.last.photo_file_name populates in Rails console (requires backend PR #2803 deployed)
• Submit without a photo → confirm JSON path still works end-to-end

Testing status — heads up

I did NOT manually run the app to test this end-to-end. All that was verified is static analysis: TypeScript, ESLint, Prettier, and the husky pre-commit hook — all clean. The backend + mobile need to be deployed together and poked manually (the issue's check step uses Rails console + Task.last.photo_file_name).

🤖 Generated with Claude Code

[stephenhungg]

Superseded by #34, which rebuilds REP-49 (mobile side) directly off main without the design-system-overhaul + REP-41 stack. Branch stays alive for now as a fallback until #34 has been manually verified on a device.