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/antigravity.fish

@@ -1,7 +1,18 @@
 # Copyright (C) 2026 Rootiest
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-# alias antigravity=agy
+# SYNOPSIS
+#   antigravity [args...]
+#
+# DESCRIPTION
+#   Wrapper for the agy Antigravity AI CLI that filters a known noisy warning
+#   about an unrecognized 'app' option from stderr.
+#
+# ARGUMENTS
+#   args...  Arguments passed through to the agy command
+#
+# EXAMPLE
+#   antigravity chat
 function antigravity --wraps='agy' --description 'alias antigravity=agy'
     # In fish, we pipe stderr using '2>|' to another command
     command agy $argv 2>| grep -v "'app' is not in the list of known options" >&2