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>

.gitignore

@@ -1,3 +1,11 @@
-plan/
-plans/
 *~
+plan/
+/target
+/target-*/
+/dist
+/corpus
+/log
+.DS_Store
+/.claude/
+/craft-fonts/
+packaging/env.sh