Connection edit sheet: "What agents see" preview shows an inventory line agents no longer read, and the account label is not display-only

[sergical]

Problem

In the connection edit sheet (packages/react/src/components/metadata-edit-sheet.tsx, ConnectionEditSheet), the "What agents see" preview renders:

- `<prefix>` — <description>

That is the per-connection line the execute tool description used to carry. #1230 slimmed the inventory to bare integration slugs (packages/core/execution/src/description.ts, formatIntegrationInventory), so no agent reads that line any more. The preview now shows text that does not exist on any agent-facing surface.

Two related copy problems in the same sheet:

• The Account label field says "Display-only; shown in the accounts list instead of the connection name." But connections.list returns identityLabel to agents next to description (packages/core/sdk/src/core-tools.ts, connectionToListItem). Editing the label does change what an agent sees on its next connections.list call.
• The sheet description says the description "rides this connection's prefix in the tool inventory", which is the removed format.

The doc comment on Connection.description in packages/core/sdk/src/connection.ts describes the same removed surface.

Why it matters

A user who edits the account label expects the "What agents see" preview to reflect it, since the callable name was derived from the label they typed at connect time. Today the preview does not move, the help text says the label is display-only, and both statements are wrong: the label is agent-visible via connections.list, and the preview shows a format agents never read.

The callable name itself (tools.<integration>.<owner>.<connection>) is correctly fixed at connect time: saved code and artifacts call that path, so it should not follow a label rename. The sheet should say so instead of implying the label has no agent-facing effect.

Reproduce

1. Add a connection with a typed label, e.g. "Prod Gmail".
2. Open the connection's edit sheet and change the account label to "Staging Gmail".
3. The "What agents see" preview does not change, and the help text says the label is display-only.
4. From an agent, call connections.list: the item carries identityLabel: "Staging Gmail".

Proposed fix

Render the connections.list item (name, identityLabel, description) in the preview, update the sheet copy to say both fields are agent-visible while the callable name stays fixed at connect time, and refresh the Connection doc comments.