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/diagnostics.md

@@ -0,0 +1,75 @@
+---
+title: Diagnostics - Errors and Warnings in Zed
+description: View and navigate errors, warnings, and code diagnostics from language servers in Zed.
+---
+
+# Diagnostics
+
+Zed gets its diagnostics from the language servers and supports both push and pull variants of the LSP which makes it compatible with all existing language servers.
+
+# Regular diagnostics
+
+By default, Zed displays all diagnostics as underlined text in the editor and the scrollbar.
+
+Editor diagnostics could be filtered with the
+
+```json [settings]
+"diagnostics_max_severity": null
+```
+
+editor setting (possible values: `"off"`, `"error"`, `"warning"`, `"info"`, `"hint"`, `null` (default, all diagnostics)).
+
+The scrollbar ones are configured with the
+
+```json [settings]
+"scrollbar": {
+  "diagnostics": "all",
+}
+```
+
+configuration (possible values: `"none"`, `"error"`, `"warning"`, `"information"`, `"all"` (default))
+
+The diagnostics could be hovered to display a tooltip with full, rendered diagnostic message.
+Or, `editor::GoToDiagnostic` and `editor::GoToPreviousDiagnostic` could be used to navigate between diagnostics in the editor, showing a popover for the currently active diagnostic.
+
+# Inline diagnostics (Error lens)
+
+Zed supports showing diagnostic as lens to the right of the code.
+This is disabled by default, but can either be temporarily turned on (or off) using the editor menu, or permanently, using the
+
+```json [settings]
+"diagnostics": {
+  "inline": {
+    "enabled": true,
+    "max_severity": null, // same values as the `diagnostics_max_severity` from the editor settings
+  }
+}
+```
+
+# Other UI places
+
+## Project Panel
+
+Project panel can have its entries coloured based on the severity of the diagnostics in the file.
+
+To configure, use
+
+```json [settings]
+"project_panel": {
+  "show_diagnostics": "all",
+}
+```
+
+configuration (possible values: `"off"`, `"errors"`, `"all"` (default))
+
+## Editor tabs
+
+Similar to the project panel, editor tabs can be colorized with the
+
+```json [settings]
+"tabs": {
+  "show_diagnostics": "off",
+}
+```
+
+configuration (possible values: `"off"` (default), `"errors"`, `"all"`)