M0: workspace, model, geometry, fonts, text, renderer, engine, MCP and CLI

Clean-room PowerPoint-class presentation engine in pure Rust:
- geom: units, transforms and 150+ re-derived preset shapes with adjust handles
- color: theme slots and colour transforms
- model: presentations, masters, 11 layouts, placeholder inheritance, themes,
  text, tables, charts, transitions, animations, text edit operations
- fonts: font DB with craft-fonts, system fonts and open substitutes
- text: shaping, line breaking, bullets/numbering, alignment, autofit, caret hit tests
- render: vello_cpu slides with fills, gradients, pictures, effects, tables, charts
- format: native .slidecraft (zip + JSON)
- engine: ~200 commands, undo/redo, clipboard, pointer tools, keys, sample deck
- mcp: MCP server (headless or bridged to the app); slidecraft-cli

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -0,0 +1,17 @@
+# SlideCraft — working notes for Claude
+
+Read [AGENTS.md](AGENTS.md) first: its rules (asset policy, clean room, never crash) bind you and
+win over anything here.
+
+## Start every session
+1. Read `plan/STATUS.md`, then the current milestone in `plan/execution-plan.md`.
+2. Read `../../craftrules/AGENTS.md` and the standards it lists for your task.
+3. Run `cargo xtask ci` before you change anything, so you know the tree is green.
+
+## Habits
+- Every user-visible action is a command with tests (`crates/engine/src/cmd/*`).
+- Look at UI changes: `slidecraft --sample --control 7979` + `ui.screenshot`, or
+  `slidecraft-cli render`.
+- Commit after each landed arc (`M<n>.<k>: what`) and push to `origin main`.
+- Keep `ROADMAP.md` and `plan/STATUS.md` current.
+- Don't ask the user questions; record genuinely-theirs decisions in `plan/STATUS.md`.