logiguard fork: GPUI xdg-activation keyboard-focus serial fix

Single-commit orphan branch: full zed-industries/zed @ 8c74db0 source tree
with a 3-file patch applied (no upstream history).

Patch (crates/gpui_linux/src/linux/wayland/):
  - serial.rs: add SerialKind::KeyboardEnter
  - client.rs: store wl_keyboard.enter serial; add latest_serial_of()
  - window.rs: activate() uses keyboard-enter serial (Mutter focus gate)

Mutter honors window activation only when the token carries the keyboard-
focus serial from wl_keyboard.enter; GPUI used a stale mouse-press serial.
See docs/tray-window-focus-wayland.md in logiguard.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/src/collaboration/contacts-and-private-calls.md

@@ -0,0 +1,29 @@
+---
+title: Contacts and Private Calls
+description: "Add contacts and start private collaboration sessions in Zed."
+---
+
+# Contacts and Private Calls {#contacts}
+
+Private calls provide ad-hoc collaboration sessions outside of channels. Add contacts to your list and start calls with one or more people.
+
+## Adding a Contact
+
+1. In the Collaboration Panel, click the `+` button next to the `Contacts` section
+1. Search for the contact using their GitHub handle.\
+   _Note: Your contact must be an existing Zed user who has completed the GitHub authentication sign-in flow._
+1. Your contact will receive a notification.
+   Once they accept, you'll both appear in each other's contact list.
+
+## Private Calls
+
+To start a private call:
+
+1. Click the `...` menu next to an online contact's name in the Collaboration Panel.
+1. Click `Call <username>`
+
+Once you've begun a private call, you can add other online contacts by clicking their name in the Collaboration Panel.
+
+---
+
+_Private calls work like [channels](./channels.md), without channel-specific features such as channel notes._