fix(functions): split dops.fish into dops and docker

dops.fish defined `docker`, not `dops`. dops was never defined; docker
was only conditionally defined as a side effect of the failed dops
autoload, so its behavior could silently change mid-session. See
JOB-BRIEF-FINDINGS.md §1.

- functions/dops.fish now defines dops: a real enhanced `docker ps`
  listing (custom Names/Image/Status/Ports table), with its own --help.
- functions/docker.fish is a new file holding the ps-redirect wrapper,
  fixed to actually call dops (previously called the still-undefined
  dops from inside itself).
- Bare `docker` with no arguments no longer falls through an
  if-with-no-else (the fish false-zero, AGENTS.md standing gotcha #5)
  and does nothing; it now runs the real docker binary, which prints
  its own usage.
- tests/functional.fish: updated the now-stale comment explaining why
  the help-flag check resolves the real function name instead of the
  file stem.

functions/docker.fish

@@ -0,0 +1,41 @@
+# Copyright (C) 2026 Rootiest
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+# CATEGORY
+#   12-ai-and-developer-tools
+#
+# DEPENDENCIES
+#   dops
+#
+# SYNOPSIS
+#   docker [subcommand] [args...]
+#
+# DESCRIPTION
+#   Wrapper for docker that intercepts the ps subcommand and redirects it to
+#   the dops function for enhanced container listing. All other subcommands,
+#   and a bare invocation with no subcommand, are passed through to the real
+#   docker binary.
+#
+# ARGUMENTS
+#   subcommand  Docker subcommand (ps is redirected to dops)
+#   args...     Arguments forwarded to docker or dops
+#
+# EXIT STATUS
+#   Exit status of dops (for ps), or of the real docker binary otherwise
+#
+# EXAMPLE
+#   docker ps
+#   docker
+function docker --description 'Execute docker, redirecting ps to the enhanced dops listing'
+    if test -z "$argv[1]"
+        command docker
+        return
+    end
+
+    switch $argv[1]
+        case ps
+            dops $argv[2..-1]
+        case '*'
+            command docker $argv[1..-1]
+    end
+end