refactor(theme): remove the Night profile (Dreamcoder is Light and Dark only)

[Dreamcoder08]

Summary

The design system has exactly two modes, Dreamcoder Light and Dreamcoder Dark. The Night render profile (derived from Dark) is removed end to end. The scheduler never activated it and the 16:00 timer trigger only re-applied Light.

Changes

• Night removed from palette, settings, renderer contract, targets manifest/schema, tokens and every renderer
• dreamcoder night rejected as an unknown command; apply-theme-mode.sh and theme-auto.sh drop the profile argument
• 33 generated *-night* artifacts deleted (Herdr, Kitty, Starship, Ghostty, Warp, ...)
• Live docs and specs rewritten for Light/Dark; timer keeps 07:00 (light) and 18:00 (dark)
• A legacy persisted theme.render_profile is ignored as an unknown setting

Verification

Every tracked *dark*/*light* artifact is byte-identical to the pre-change baseline; full suites green. Size: 768 authored additions and 5,383 deletions, of which ~2.9k are generated Night artifacts and ~2.1k removed Night code; no cohesive split fits 400 lines, so a size:exception is recommended.

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	5 of 6
Base	pr/04-shell-safety
Depends on	#14
Follow-up	#16
Review budget	6151 / 400
Starts at	the tip of pr/04-shell-safety
Ends with	refactor(theme): remove the Night profile (Dreamcoder is Light and Dark only)

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:
• Legacy Dusk token set (still used; separate decision)
• Archived openspec, CHANGELOG and docs/superpowers history

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