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/__tests__/desktop-env.test.js

@@ -8,7 +8,7 @@
  */
 const { describe, it, beforeEach, afterEach } = require("node:test");
 const assert = require("node:assert/strict");
-const { desktopEnv, FORWARDED, __setExecImpl } = require("../lib/desktop-env");
+const { desktopEnv, canReadClipboard, FORWARDED, __setExecImpl } = require("../lib/desktop-env");
 
 const saved = {};
 
@@ -61,3 +61,30 @@ describe("desktopEnv", () => {
     assert.equal(desktopEnv().WAYLAND_DISPLAY, undefined);
   });
 });
+
+describe("canReadClipboard", () => {
+  const has =
+    (...names) =>
+    (n) =>
+      names.includes(n) ? `/usr/bin/${n}` : null;
+
+  it("needs wl-paste for a Wayland display, xclip for an X one", () => {
+    const wl = { WAYLAND_DISPLAY: "wayland-0" };
+    const x = { DISPLAY: ":0" };
+    assert.equal(canReadClipboard({ platform: "linux", env: wl, which: has("wl-paste") }), true);
+    assert.equal(canReadClipboard({ platform: "linux", env: wl, which: has("xclip") }), false);
+    assert.equal(canReadClipboard({ platform: "linux", env: x, which: has("xclip") }), true);
+    assert.equal(canReadClipboard({ platform: "linux", env: x, which: has() }), false);
+  });
+
+  it("is false with no display at all — a headless box", () => {
+    assert.equal(
+      canReadClipboard({ platform: "linux", env: {}, which: has("xclip", "wl-paste") }),
+      false
+    );
+  });
+
+  it("is true off Linux, where the clipboard tools are built in", () => {
+    assert.equal(canReadClipboard({ platform: "darwin", env: {}, which: has() }), true);
+  });
+});