MCP server: modelcraft-cli mcp (headless or bridged), read/write roots, end-to-end analysis over MCP (#48)

* io: read and write roots that confine an automation client's file access

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* engine: every file a command reads or writes is checked against the session's roots

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* engine: headless pictures of a session (model, geometry, deformed shape and contours)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* mcp: MCP server over stdio with headless and connected backends, roots and caps

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* cli: modelcraft-cli mcp [--connect ADDR | --headless] with automation read and write roots

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* mcp: end-to-end analysis of a corpus part over MCP (open, tet mesh, define, solve, probe, render)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* docs: MCP server (docs/mcp.md), Claude Code setup, roots; architecture, README, roadmap, attribution

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

---------

Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/testkit/src/corpus.rs

@@ -224,15 +224,18 @@ pub fn parts() -> Result<Vec<Part>> {
     Ok(parts)
 }
 
-/// Build a part: run its recipe (or generate the shape) and open the design.
-pub fn load(part: &Part) -> Result<Design> {
-    let geometry = |source| Error::Geometry { part: part.name.clone(), source };
-    let bytes = match &part.source {
+/// A part's design as `.solidcraft` bytes: its recipe run (or its shape generated).
+pub fn design_bytes(part: &Part) -> Result<Vec<u8>> {
+    match &part.source {
         Source::Recipe(script) => script_design(script),
         Source::Analytic(shape) => shape.design(),
     }
-    .map_err(geometry)?;
-    open_design(&bytes).map_err(geometry)
+    .map_err(|source| Error::Geometry { part: part.name.clone(), source })
+}
+
+/// Build a part: run its recipe (or generate the shape) and open the design.
+pub fn load(part: &Part) -> Result<Design> {
+    open_design(&design_bytes(part)?).map_err(|source| Error::Geometry { part: part.name.clone(), source })
 }
 
 #[cfg(test)]