fix: per-user Today, native paste and drop on a local machine

- Today's spend in the status bar and the Claude Code statusline is the
  caller's own (`GET /api/pricing/cost?mine=1`, scope.ownSessionWhere), not
  every user's sum for an admin or analyst.
- A screenshot pasted into a local claude pane is sent as Claude Code's own
  image-paste key: Alt+V on Windows (Ctrl+V did nothing there), ^V elsewhere,
  and only when the machine can read its clipboard (wl-paste/xclip + a
  display on Linux), else it is uploaded (GET /api/run/native-paste {key}).
- A file manager's files pasted or dropped on a local browser go in by their
  own paths, read from the OS clipboard or the file manager's selection
  (server/lib/file-manager.js, POST /api/run/clipboard-files and
  /selected-files): no upload, no size limit. A copied image file is pasted
  by path, text that comes with a picture of it (spreadsheet cells) is
  pasted as text, Windows paths go in as `C:/…` mentions.
- Tab titles for Snapshot, Artifacts, Files and Administration.
- An npm tool AgentHub installed under ~/.local is updated there, not by its
  own updater into npm's global prefix.

server/lib/desktop-env.js

@@ -64,4 +64,22 @@ function desktopEnv() {
   return out;
 }
 
-module.exports = { desktopEnv, FORWARDED, __setExecImpl };
+/**
+ * Whether a CLI in a pane started now can read this desktop's clipboard — what
+ * a native image paste (`^V`, the terminal's `lib/nativePaste.ts`) relies on.
+ * On Linux Claude Code shells out to `wl-paste` (Wayland) or `xclip` (X11);
+ * neither ships with a stock Ubuntu, and with neither — or with no display to
+ * reach — the `^V` pastes nothing at all, so the browser must upload instead.
+ * macOS and Windows read their clipboard with built-in tools.
+ */
+function canReadClipboard({
+  platform = process.platform,
+  env = null,
+  which = (name) => require("./ai-tools").which(name),
+} = {}) {
+  if (platform !== "linux") return true;
+  const e = env || desktopEnv();
+  return !!((e.WAYLAND_DISPLAY && which("wl-paste")) || (e.DISPLAY && which("xclip")));
+}
+
+module.exports = { desktopEnv, canReadClipboard, FORWARDED, __setExecImpl };