v3.23.1 — Resizable diagram editor, issue template enforcement

What's New

Resizable Split Pane (#525)

• Code pane defaults to 30% width (was 50/50)
• Draggable split handle between code and preview (10–70% range)
• Handle highlights blue on hover/drag

Issue Template Enforcement (#526)

• 7 required sections (was 3): Goal, Context, Acceptance Criteria, Affected Files, Related Issues, Verification Steps, Definition of Done
• epic-decompose now reads issue.xml template before creating tasks
• issue-structure.xml added to plugin-pm — survives installation
• priority (critical/high/medium/low) and effort (S/M/L/XL) in frontmatter

Enhanced PRD Template (#526)

• Architecture Design section — component tree, data flow, state management
• Phased execution — Analyze → Foundation → Core → Polish
• Quick Win Path — minimum viable demo in 1–3 days

Full Changelog: v3.23.0...v3.23.1