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/rg.fish

@@ -1,7 +1,19 @@
 # Copyright (C) 2026 Rootiest
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-# alias rg=rg --hyperlink-format=kitty
+# SYNOPSIS
+#   rg [args...]
+#
+# DESCRIPTION
+#   Wraps ripgrep with --hyperlink-format=kitty when running inside Kitty
+#   terminal, enabling clickable file links in search results. Falls back
+#   to plain rg on other terminals.
+#
+# ARGUMENTS
+#   args...  Arguments forwarded to ripgrep
+#
+# EXAMPLE
+#   rg "TODO" src/
 function rg --description 'alias rg=rg --hyperlink-format=kitty'
     if test "$TERM" = xterm-kitty
         command rg --hyperlink-format=kitty $argv