Replace the single attach popover with an Open WebUI-style multi-level
menu covering every attachment source:
- Upload Files: images stay inline (vision); other files are uploaded and
grounded via retrieval (`file-{id}` collection).
- Capture: take a photo from the webcam as an inline image.
- Attach Webpage: ingest a URL (existing).
- Attach Files: pick files already stored in Open WebUI.
- Attach Notes: inject the contents of a note as context.
- Attach Knowledge: nested picker with checkboxes, expandable to a base's
files (replaces the flat checkbox list).
- Reference Chats: bring a previous conversation in as context.
Knowledge bases, web pages and files are grounded by retrieval; notes and
referenced chats are injected verbatim as context blocks. Adds the
supporting integration methods (list files/notes, knowledge files, upload
file), request handlers and tRPC procedures.
Lok3sh-Kumar
78bd66e803