docs(functions): standardize all function doc blocks to UNIX man-page style

Replace all ad-hoc inline comments between license headers and function
declarations with consistent SYNOPSIS / DESCRIPTION / ARGUMENTS / RETURNS /
EXAMPLE blocks across all 99 project-owned functions/ files. No executable
logic, variable names, or exit codes were modified.

Completes Task #6 from AGENTS.md (Retroactive Function Documentation
Standardization).

functions/lock.fish

@@ -1,7 +1,14 @@
 # Copyright (C) 2026 Rootiest
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-# alias lock=loginctl
+# SYNOPSIS
+#   lock
+#
+# DESCRIPTION
+#   Locks the current desktop session using loginctl lock-session.
+#
+# EXAMPLE
+#   lock
 function lock --wraps='loginctl' --description 'alias lock=loginctl'
     loginctl lock-session
 end