docs: consolidate and archive completed work

Move planning/implementation documents to .archive/completed-work/:
- PLAN-UNIFY.md — v0.9.0 unification strategy (implemented)
- IMPLEMENTATION-PLAN.md — shell module specs (merged)
- CLAWDIE-ISO-REFACTORED.md — split ISO work (unified)
- CLAWDIE-SHELL.md — archived repo docs
- POUDRIERE-IMPLEMENTATION.md — old package system
- REFACTOR-SUMMARY.md — old refactoring notes

Add CHANGELOG.md:
- Consolidate release notes in single growing file
- Track breaking changes, new features, improvements
- Repository status summary
- Future roadmap (v1.0.0)

Why: Post-merge cleanup. Planning phase complete, code now merged.
Progress files remain accessible in .archive/ but don't clutter root.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -0,0 +1,76 @@
+# Clawdie Changelog
+
+All notable changes to Clawdie-ISO are documented here.  
+For detailed release notes, see `RELEASE-NOTES-*.md` files.
+
+---
+
+## [0.9.0] — 2026-04-06
+
+**Codename:** Unified Architecture
+
+### Breaking Changes
+- ✂️ Unified ISO: Single `./build.sh` builds for all targets (VPS, baremetal, cloud)
+- ✂️ Removed `--target` and `--gpu-driver` flags (runtime detection now handles this)
+- ✂️ Deprecated `doas` — all privileged operations now use `sudo`
+- ✂️ clawdie-shell repo archived (merged into clawdie-iso)
+
+### New Features
+- 🎯 Runtime GPU detection (Intel, AMD, NVIDIA 390/470/590)
+- 🎯 Runtime display detection (VPS headless, baremetal with Lumina desktop)
+- 🎯 PF firewall with glasspane VNC (secure remote browser access)
+- 🎯 Tailscale integration (mandatory, with optional opt-out)
+- 🎯 8 shell modules for modular firstboot orchestration
+- 🎯 Automatic sudo fallback for pkg operations (privilege escalation)
+
+### Improvements
+- 📈 Comprehensive REQUIREMENTS.md (pre-install checklist)
+- 📈 NETWORKING.md with architecture diagrams
+- 📈 SHELL-MODULES.md with all 8 module specifications
+- 📈 BUILD.md with detailed build process
+- 📈 Integration tests for full module flow validation
+- 📈 Preflight validation scripts
+
+### Deprecations
+- ⚠️ PLAN-UNIFY.md (archived — planning complete)
+- ⚠️ IMPLEMENTATION-PLAN.md (archived — implementation merged)
+- ⚠️ clawdie-shell repo (archived — use clawdie-iso main)
+
+### Performance
+- ISO size: 50 GB (includes all packages for offline installation)
+- Build time: ~13 minutes (with package cache)
+- GPU support: 3 NVIDIA versions + AMD + Intel firmware (all bundled)
+
+---
+
+## Repository Status
+
+| Repo | Status | Latest |
+|------|--------|--------|
+| clawdie-ai | Active | v0.9.0 |
+| clawdie-iso | Active | v0.9.0 + Phase 0 |
+| clawdie-shell | **Archived** | — |
+| pi | Independent | v0.56.3 |
+
+---
+
+## Archive
+
+Completed work (planning, implementation notes, refactors) has been moved to `.archive/completed-work/`:
+- PLAN-UNIFY.md — v0.9.0 unification strategy (now implemented)
+- IMPLEMENTATION-PLAN.md — shell module implementation (now merged)
+- CLAWDIE-ISO-REFACTORED.md — split ISO refactoring (now unified)
+- CLAWDIE-SHELL.md — shell-specific docs (repo archived)
+- POUDRIERE-IMPLEMENTATION.md — old package system work
+- REFACTOR-SUMMARY.md — old refactoring notes
+
+---
+
+## For v1.0.0
+
+- [ ] Qt6 GUI foundation for firstboot wizard
+- [ ] GPU detection GUI with C++ backend
+- [ ] Multi-page wizard (Tailscale, Identity, GPU, Packages)
+- [ ] Replace bsdinstall text UI with Qt6 version
+- [ ] Hardware testing on 3+ configurations
+- [ ] Admin panel with bsddialog menus