Switch UX/UI tooling to self-hosted Penpot; add setup checklist

- ux-designer.md: replace Figma with Penpot REST API approach; add
  next-session checklist (LXC setup, project creation, access token,
  component library decision, agent connection)
- TODO.md: add Penpot setup section with five actionable items
- changelog: document the tooling decision and rationale

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

changelog/2026-04-13_penpot-decision.md

@@ -0,0 +1,20 @@
+# 2026-04-13 — Switch UX/UI tooling to self-hosted Penpot
+
+**Timestamp:** 2026-04-13T03:00:00
+
+## Summary
+
+Decided to use self-hosted Penpot instead of Figma for UX/UI design work. Penpot will run in a dedicated LXC container on the user's server; the `ux-designer` agent connects to it via the Penpot REST API using WebFetch — no MCP server required. Setup is pending for the next session.
+
+## Decision rationale
+
+- Full self-hosting control, no SaaS dependency or monthly cost
+- Penpot REST API is directly accessible via WebFetch (no MCP server needed)
+- User is experienced with self-hosting Docker/LXC infrastructure
+- Open-source (MPL 2.0), actively maintained
+
+## Files Modified
+
+- `.claude/agents/ux-designer.md` — replaced Figma MCP instructions with Penpot REST API setup guide; added ⚠ next-session checklist with all steps to complete before UX work can begin
+- `TODO.md` — added UX/UI Penpot setup section with five actionable items
+- `changelog/2026-04-13_penpot-decision.md` — this file