Experimental inputs UI improvements #2263

[0Cymantek0]

Issues

• Experimental PR based on : UI/UX improvements for project creation inputs: batching, staged files summary, and bounded layout #2263

Changes

1. Reject directory uploads

• Detect and reject dropped folders using webkitGetAsEntry().isDirectory.
• Display a docked warning notice indicating the number of skipped folders.
• Update docs/inputs.rst to note that directory uploads are unsupported and must be uploaded as archives (.zip, .tar.gz).

Before	After

2. Staged files summary header and batch controls

• Add a sticky header above the inputs list displaying total file count, formatted combined size, and a "Delete all" button.
• Accumulate multi-step selections across repeated drops or picker selections instead of overwriting prior selections.

Before	After

3. Layout bounds and pinned project form actions

• Bound the file inputs list height with vertical scrolling (max-height: 180px) and scrollbar-gutter: stable to prevent page expansion and layout shifts.
• Bound the download URLs textarea with internal vertical scrolling.
• Keep the project form submission controls pinned to the bottom of the viewport so action buttons remain accessible while managing long input lists.

Before	After

4. Delete button on long file names made accessible

• Previously, when a file with a very long name was uploaded, the delete button was pushed out of bounds making it unclickable. Now that has been fixed with ellipsis and flex shrink boundaries.

Before	After

Checklist

• I have read the contributing guidelines
• I have linked an existing issue above
• I have added unit tests covering the new code (N/A: frontend vanilla JS/CSS changes; verified manually and existing test suite passes)
• I have reviewed and understood every line of this PR