feat: wire public-visibility uploads through the external-signer flow

[Nic-dorman]

Summary

Re-enables the Public visibility option in the upload dialog (currently disabled with "Coming soon") by threading a visibility flag through the external-signer flow. Public uploads yield a single shareable on-network chunk address (the published DataMap); the public_address is surfaced on UploadResult so the UI can show / copy it.

• Why not data_map_store after finalize_upload? That path hard-requires require_wallet()?; ant-gui has no Rust-side wallet on the WalletConnect path — all signing goes via the frontend. store_paid_chunks and friends are pub(crate). Upstream's file_prepare_upload_with_visibility bundles the DataMap chunk into the existing one-signature payment batch, which is what lets ant-gui thread a visibility flag through its existing code path.

Changes

Backend (src-tauri)

• autonomi_ops.rs
  • Imports ant_core::data::Visibility.
  • StartUploadRequest gets an optional visibility: Option<String> (serde default → Private).
  • start_upload calls client.file_prepare_upload_with_visibility(&path, visibility).
  • confirm_upload and confirm_upload_merkle extract result.data_map_address into UploadResult.public_address (hex-encoded, 0x…, or None for private uploads).
  • wallet_upload (direct-key path) also populates UploadResult.public_address defensively from result.data_map_address. Today this is always None because direct-key mode doesn't thread visibility yet — wiring it through wallet_upload is a small follow-up if you want devnet/direct-key Public uploads too.
• config.rs — UploadHistoryEntry.public_address: Option<String> persisted to upload_history.json.

Frontend

• stores/files.ts
  • getUploadQuote(path, visibility = 'private') accepts visibility and forwards it to start_upload. Docstring explains the prepared-batch / visibility-pinning constraint.
  • FileEntry.visibility and UploadHistoryEntry.public_address propagated through history load/save.
• components/files/UploadConfirmDialog.vue
  • Public radio re-enabled as a real option (was disabled).
  • New visibility-change emit fires on toggle so the parent can re-quote (public batches cost one extra chunk).
• pages/files.vue
  • onVisibilityChange(visibility) updates each selected entry's visibility in the store. The store-driven scheduler / Approve handler already pass visibility through, so the per-entry state stays synced when the user toggles in the dialog.
  • Uploads table shows a "Public" badge on rows with a public_address; clicking copies the address.

Test plan

• cargo check --all-targets clean against ant-core-v0.2.2
• cargo clippy --all-targets -- -D warnings clean
• cargo fmt --check clean
• CI green (Linux). Local Windows vitest is hitting a known npm optional-deps flake unrelated to this PR.
• Manual: upload a file with Public selected → verify a 64-char hex address appears on the row with a Public badge → click it → verify clipboard contents.
• Manual: upload with Private selected → row still shows the datamap filename (existing behaviour unchanged).
• Manual: fresh download of a public upload via "Download by Address" using the copied address → verify download_public fetches the DataMap off-network and decrypts correctly.

Rebase notes

This branch was rebased onto post-bump main (which now includes the live-progress work from #65 + the ant-core 0.2.2 dep bump) and lost a couple of segments that were superseded:

• Pre-quote machinery (pendingUploadFiles, pendingQuotes, quotedVisibility, startQuoting, the watch(autonomiConnected) re-quote trigger) was dropped in favour of main's store-driven scheduler.
• The "drop pre-quote if visibility flipped after Approve" guard was dropped along with the pre-quote state — main re-queries through the store rather than pinning a single pre-quote per dialog session. Public/Private cost-difference UX could be added back as a follow-up.
• effectivePaymentMode in the dialog now uses main's per-entry estimate; the AVG_CHUNK_SIZE/MERKLE_THRESHOLD heuristic from this branch was removed.
• The two stale fix(nodes): … commits that were sitting on this branch locally were dropped during rebase — they're already on main via fix(nodes): honour storage dir setting + show real storage usage #34.