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/top.fish

@@ -1,7 +1,18 @@
 # Copyright (C) 2026 Rootiest
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-# Use btop as a modern replacement for top
+# SYNOPSIS
+#   top [args...]
+#
+# DESCRIPTION
+#   Wraps btop as a modern replacement for top. Falls back to system top
+#   if btop is not installed.
+#
+# ARGUMENTS
+#   args...  Arguments forwarded to btop or system top
+#
+# EXAMPLE
+#   top
 function top --wraps='btop' --description 'Use btop as a modern replacement for top'
     # 1. Check if btop is actually installed
     if type -q btop