fix(send): make the mobile file info panel dismissable and non-blocking (#977)

[aaspinwall]

What changed?

On the Your Files page, the file info panel now behaves correctly on mobile:

• HomeView.vue — the info panel is the original inline w-64 column on desktop (md+), but below md it becomes a full-screen, dismissable overlay (max-md:-scoped classes, so desktop layout is unchanged). It only renders when a file/folder is actually selected.
• FileInfo.vue — added a close (X) button and a delete button, reusing the existing DeleteModal + DeleteConfirmation flow already used by FolderView.
• FolderInfo.vue — added a matching close button (it shares the same overlay).
• FolderView.vue — file-row download/delete buttons are now visible on mobile instead of hover-only, so the row delete button is tappable on touch.
• folder-store.ts — added clearSelection(), used by the new close controls and by deleteItem.
• e2e — added a Firefox mobile-viewport (412px) Playwright suite (playwright.config.mobile977.ts + tests/mobile/dev/file-info-panel.spec.ts) that registers a user, uploads a file, opens the info panel, and asserts the close and delete controls work and the panel dismisses.

AI disclosure: This change was implemented by Claude (agentic), with the author directing the task, reviewing the diff and screenshots, and approving the approach. A senior-code-review pass was run over the diff and its suggestions applied.

Why?

Per #977, on a mobile browser the file info panel covered the file's delete button, had no delete button of its own, and could not be closed (it even persisted across navigation). This made it impossible to delete a file once the panel was open. The panel is now an overlay that doesn't cover the list, can be closed, and can itself delete the file.

Limitations and Notes

• The desktop info-panel layout is intentionally left byte-for-byte identical; only sub-md behavior changed.
• Verified manually via the new Playwright suite at a Pixel-sized viewport (screenshots captured locally: panel-open with close+delete, panel-closed with row buttons visible, delete confirmation, and post-delete empty state).
• The pre-existing desktop dev e2e suite (--grep @dev-desktop) is flaky (share-link/session timing, see Flaky Send E2E: 'No Group found' after register/login leaves folder view empty, cascades into folder-row/goto failures #930) and fails a few tests on a clean tree as well; that is unrelated to this change.

Applicable Issues

Closes #977

Screenshots

Captured by the new mobile suite: the info panel renders as a full-screen overlay with a close (X) and a red delete button; after closing, the file list and its row delete buttons are fully accessible.

🤖 Generated with Claude Code

[rwood-moz]

I can see the new panel that can be closed (and has the new delete button) on desktop; but when I open it in the Playwright Google Pixel 10 viewport, the panel has the new close button X top right; but there is no delete or download button. I see in your mobile viewport E2E tests it is there though, so I don't know what is happening here. I'll try on main and see if the panel shows the download button.

Screen.Recording.2026-07-10.at.11.11.38.AM.mov

[rwood-moz]

I can see the new panel that can be closed (and has the new delete button) on desktop; but when I open it in the Playwright Google Pixel 10 viewport, the panel has the new close button X top right; but there is no delete or download button. I see in your mobile viewport E2E tests it is there though, so I don't know what is happening here. I'll try on main and see if the panel shows the download button.

Yes on main the Google Pixel 7 viewport does show the download button in the file info panel, so there must be an issue with the new info panel on this PR/branch.

This is the viewport I'm using (Google Pixel 7, NOT 10 like I mentioned above, sorry):

    {
      name: 'Google-Pixel-7-View',
      use: {
        ...devices['Pixel 7'],
        screenshot: 'only-on-failure',
       },
    },