findReferences

Ask the server to locate all references to the symbol at the cursor and, when any are returned, show them in a panel.

Ports upstream @codemirror/lsp-client's findReferences command:

• resolves this editor's ReferenceServer binding from the referenceServer facet; returns false (command not handled) when none is installed,

• returns false when the server explicitly lacks referencesProvider,

• otherwise flushes pending edits (LSPClient.sync), issues textDocument/references at the cursor (with includeDeclaration = true, matching upstream), and opens the reference panel with the resulting locations.

The suspending work runs on the client scope (not the session's) because navigating to a result may target a different editor session that must outlive the requesting one. Cancellation of the in-flight LSP call is cooperative through structured concurrency, consistent with the other LSP features.