fix(ml4w): keep Dreamcoder working on ML4W 2.16

[Dreamcoder08]

Summary

ML4W 2.16 moved the Quickshell overview, dropped Waybar/waypaper pieces and rewrites the files Dreamcoder used to inject hooks into. This slice makes the ML4W integration survive upgrades and pins the new upstreams.

Changes

• Keybind variant aligned with ML4W 2.16 (overview path, autohide toggles, AZERTY detection)
• Wallpaper hook as a marked, idempotent block in ml4w-wallpaper; waypaper hooked only when present
• dreamcoder-colors loaded from custom.lua (a file ML4W never ships)
• verify/doctor accept sync-rendered regular colour files and waybar/colors.css
• dreamcoder dispatcher exports PYTHONPATH for every Python route
• Upstream pins: ML4W 2.16 (3960570), Gentleman.Dots 6f44b79

Verification

bats tests/ml4w/ and python -m pytest tests/ green on the slice tip; shellcheck and luac -p clean; applied and verified on a live ML4W 2.16 machine (verify-ml4w-setup.sh 20 passed / 0 failed).

Chain Context

Field	Value
Chain	ML4W 2.16 + Herdr 0.9.1 + Light/Dark-only stabilisation
Tracker PR	Not needed (stacked PRs to main)
Position	1 of 6
Base	main
Depends on	None (targets main)
Follow-up	#12
Review budget	1177 / 400
Starts at	main
Ends with	fix(ml4w): keep Dreamcoder working on ML4W 2.16

Chain Overview

main
 └── 📍 #11 fix(ml4w)
  └── #12 fix(install)
   └── #13 fix(theme)
    └── #14 fix(shell)
     └── #15 refactor(theme)
      └── #16 chore(quality)

Scope

• Includes: see Changes above
• Excludes:
• Stow relinking and Herdr (PR 2)
• Mode/colour stability and the GTK listener hook (PR 3)

Autonomy

• CI is expected to pass for this PR branch
• This PR has one deliverable scope
• This PR can be rolled back without unrelated changes
• Tests, docs, or manual verification cover this unit