0.10.1: Archify Sync in the status bar, server address as a setting

In workspaces with Archify files, Archify Sync sits in the status bar and
opens a menu: sign in, share, join, server address, settings. The new
archify.sync.server setting (empty by default) is used without asking,
and in workspace settings gives a project one server.
archify.sync.statusBar hides the entry.

README.md

@@ -140,7 +140,9 @@ Optional. Without a sync server the extension works exactly as described above a
 
 [Archify Sync](https://gitea.lego-cloud.eu/vscode-extensions/archify-vscode-ext-sync) is a small server you run yourself (one container and PostgreSQL; a Helm chart is included). With it, a model is edited by several people at once, like a shared document, and its files stay ordinary files on each person's disk, so Git, agents and every page of this extension keep working.
 
-- **Sign in.** *Archify | Sign in to Sync Server…* asks for the server's address and signs in through the browser; the session is kept in VS Code's secret storage and shows under **Accounts** as *Archify Sync*. A new server is set up first on its `/setup` page with the code from its log.
+- **Where.** **Archify Sync** in the status bar (in workspaces with Archify files) opens a menu: sign in, share a model, join one, the server address, settings. The same menu is *Archify | Sync…*. Hide the entry with `archify.sync.statusBar: false`.
+- **Server address.** Set `archify.sync.server` once (Settings › Archify › Sync, or *Archify | Set Sync Server Address…*), for example `https://archify.example.com`. Put it in the workspace settings and everyone in the project uses the same server. Left empty, the address is asked for once and remembered.
+- **Sign in.** *Archify | Sign in to Sync Server…* uses that address (or asks for it) and signs in through the browser; the session is kept in VS Code's secret storage and shows under **Accounts** as *Archify Sync*. A new server is set up first on its `/setup` page with the code from its log.
 - **Share.** *Archify | Share Model…* (also on `main.archify` in the Explorer) puts the model on the server and writes a small `.archify-sync` file next to `main.archify`: the server and the model's id, no secrets. Commit it, and everyone who clones the repository and is a member opens the shared model.
 - **Invite and join.** *Archify | Copy Invite Link* copies a link for the model; send it any way you like. Opening it (or *Archify | Join Shared Model…*) signs the person in, or up, and puts the files in an empty folder of their choice.
 - **Live.** Edits in any editor, page, Source view, by Git or by an agent reach the others within a moment. Their edits arrive in your open editors with undo intact and are saved to disk; your own unsaved work stays unsaved. The status bar shows **Archify live · 3 here**; the model page gets a **Shared** section with who is here and in which file, and each diagram card says who has it open. In the Source view and in text editors, teammates' cursors show as coloured carets with their names.